A ray of hope has emerged in the aftermath of tornadoes that obliterated a Kentucky town and killed people in five states, as managers of a destroyed candle factory said far fewer people may have died than previously feared.

President Joe Biden on Monday declared a major federal disaster in Kentucky, paving the way for additional federal aid, the White House said.

Officials had said the death toll could soar past 100 from twisters that tore through at least six states in the US Midwest and South on Friday night, while seeing little chance of finding survivors in the rubble two days on.

In Kentucky, Governor Andy Beshear estimated the death toll at 80 and said it was certain to rise above 100, but that was based on suspicion that scores were killed when a candle factory was destroyed in the small city of Mayfield.

Up to 70 people at the factory had been believed dead, but that number could be revised down to 16 or fewer, a company spokesman said, raising the possibility the governor's death toll estimate could come down significantly.

Among the 110 people who were at the factory, eight have been confirmed dead and eight were missing, said Bob Ferguson, a spokesperson for Mayfield Consumer Products.

"There were some early reports that as many as 70 could be dead in the factory. One is too many, but we thank God that the number is turning out to be far, far fewer," Ferguson told Reuters, adding that rescue teams were still searching for the eight who remained unaccounted for.

It was unclear how many factory workers Beshear was counting in his estimated death toll, which he formulated on Saturday and said on Sunday remained unchanged - at least for now.

"We're still getting information in on the candle factory. The owner has been in contact and believes he has some different information. We are trying to verify it. If so, it may be a better situation and the miracle we were hoping for," Beshear told a news conference earlier on Sunday evening.

Dakota Moore, 20, was working at the candle factory when the tornado warning came. As was the drill, everyone - about 100 people - lined up in the hallway in the centre of the building, near the bathrooms.

"My ears started ringing. I started looking around and everybody down on the other side by the women's bathroom started ducking down. The walls started coming in on that side. There was this old lady, I was trying to get to her, and the wall took me down," Moore said.

He said he tried to help another man who was stuck in rubble up to his neck, but was unable to lift him out.

"I was able to get to his neck to see if he had a pulse or anything. Flatline," he said.

Rescue workers continue to scour debris for survivors and many people without power, water or even a roof over their heads salvaged what they could.

While Kentucky was hardest hit, six workers were killed at an Amazon.com Inc warehouse in Illinois after the plant buckled under the force of the tornado.

A nursing home was struck in Arkansas, causing one of that state's two deaths. Four were reported dead in Tennessee and two in Missouri.

Nowhere suffered as much as Mayfield, a community of about 10,000 in the southwestern corner of Kentucky, where the large twisters also destroyed the fire and police stations.

The governor said the tornadoes were the most destructive in the state's history and that even the sturdiest structures of steel and brick were flattened. One twister tore across 365km of terrain.

Biden told reporters he would ask the Environmental Protection Agency to examine what role climate change may have played in fueling the storms.

The US Federal Emergency Management Agency was opening shelters and sending teams and supplies.

© RAW 2021

South Australian Premier Steven Marshall says he's hopeful extended quarantine for close contacts of COVID-19 Omicron cases can be removed soon.

SA has at least two confirmed cases of the new variant and its arrival last week prompted the state government to increase the isolation requirement for close contacts at exposure sites from seven to 14 days.

But Mr Marshall says as more information about the new strain emerges, it's hoped the extra requirements can be removed.

"We are taking a prudent approach because we do not want a massive Omicron outbreak in the lead-up to Christmas," the premier said.

"But I'm hopeful we'll have some good news for those people who are in 14 days quarantine and who are fully vaccinated later this week."

The quarantine change will be considered at Tuesday's meeting of the state's transition committee.

SA Health on Monday reported 13 new COVID-19 cases.

It said five were in people who recently arrived from interstate, four were close contacts of previous cases and two were in overseas arrivals.

A further two local infections were under review to determine the source.

Mr Marshall said it was believed the majority of the new cases involved the Delta variant.

They took SA's active infections to 65 with three people in hospital, a woman in her 50s and two men in their 30s, all in a stable condition.

More than 2000 people are in isolation after being identified as close contacts or after visiting a growing number of exposure sites.

Mr Marshall said he understood that those placed in isolation were making a "sacrifice" to ensure the majority of South Australians could experience a relatively normal Christmas.

"We appreciate that sacrifice," he said.

However, the premier said far fewer people were being required to quarantine now SA had moved away from the "elimination phase" to the "suppression phase" with its response to the coronavirus pandemic.

© AAP 2021

Australian motor sport official Michael Masi has found himself unwittingly one of the central players in one of modern sport's great dramas as his decisions shaped the incredible season-ending Formula One championship climax.

The 43-year-old F1 race director was slammed, praised and given plenty of sympathy in turn over his fateful, pressurised call to allow the Abu Dhabi Grand Prix to resume for one last, momentous lap on Sunday.

His late ruling enabled Red Bull's Max Verstappen to overtake Mercedes' Lewis Hamilton and win both the race and world title.

Masi found himself facing fury from Mercedes over his handling of the ending of a terribly-timed safety car period after Nicholas Latifi's late crash.

When the all-clear was given to resume racing, Mercedes boss Toto Wolff told the Australian over the radio: "Michael, this isn't right!"

Yet even after Wolff complained again, Masi stood his ground, defending his decision with the sharp response: "It's called a motor race. We went car racing."

Red Bull chief Christian Horner, naturally, praised Masi's decision to let racing recommence, saying: "The race director in difficult circumstances made absolutely the right call."

Yet it proved the toughest day in Masi's two-year reign as the man who oversees all F1 races.

His ultimate test came when confusion surrounded the restart after the Latifi crash, with five back markers still between Verstappen and Hamilton after the Dutchman had pitted with the safety car deployed and time running out for racing to resume.

Masi first decided lapped cars could not unlap themselves and then changed his mind so that the cars between the title rivals could get out of the way.

He had appeared to have been put under pressure by Horner, who had asked him on the radio: "Why aren't we getting these lapped cars out the way?"

Masi had at first hesitated, saying: "Because, Christian ... just give me a second. OK, my main big one is get this incident clear."

Horner persisted, "You only need one racing lap".

Masi then changed tack and his apparent volte-face, which allowed Verstappen what was almost an inevitable passport to victory on much fresher tyres, then triggered Wolff's wrath.

The messy affair still isn't over as Mercedes filed for reconsideration to the International Court of Appeal - in response to FIA stewards hours after Sunday's race rejecting a pair of protests lodged by the team.

A trio of former world champions Nico Rosberg, Damon Hill and Jenson Button had sympathy for Masi's plight.

Rosberg, the 2016 champion, called for more support in decision-making for the Australian.

"You've got to feel some compassion for him (Masi). He's got the whole world watching and he has to decide in the next 15 seconds what he's doing," Rosberg said.

"It's the last lap of the last race of the world championship, that is the ultimate, most high-pressure situation in the world, and he took his decision which gave us beautiful awesome racing and an incredible finale.

"We need to be careful. Michael's job this year has been so unbelievably difficult to manage this intense battle.

"Michael needs support this winter, there needs to be progress over frameworks and guidelines and we should be in a better position for next year."

But Hill noted that, although he understood why Masi wanted proceedings to finish with a proper race, the official had sent "messages that were contradictory".

Button noted Masi had earlier been put under pressure by Horner, who complained to him after Hamilton had not been penalised for going off the track and gaining an advantage when under pressure from Verstappen.

"Both Mercedes and Red Bull were talking to the referee (Masi) during the race and they can't be swaying the decision. It's difficult enough as it is for Michael Masi," Button said.

© AAP 2021

Mercedes is poised to contest Max Verstappen's Formula One championship victory despite stewards dismissing the team's post-race protests on Sunday.

Red Bull's Verstappen overtook Mercedes's seven-times world champion Lewis Hamilton in controversial circumstances on the last lap to win the Abu Dhabi Grand Prix and take his first crown.

Mercedes, who still won the constructors' crown for a record eighth year in a row, then protested against alleged breaches of the sporting regulations when the safety car was deployed late in the race.

One was "against the classification established at the end of the competition" and the other argued that Verstappen had overtaken Hamilton while the safety car was still deployed.

Both were dismissed but a Mercedes spokesman said the team had filed for reconsideration to the International Court of Appeal.

Verstappen had back markers between him and Hamilton after pitting with the safety car deployed and time running out for racing to resume.

In an unusual move, Australian race director Michael Masi first decided lapped cars could not unlap themselves and then changed his mind so that the five cars between the title rivals could get out of the way.

That gave Verstappen a clear run on Hamilton in what amounted to a last-lap sprint finish, with the Dutch driver on fresher tyres.

The finish angered Mercedes boss Toto Wolff, who demanded "the last lap be reinstated".

But Masi was firm in his reply.

"Toto, it's called a motor race," he said. "We went car racing."

Stewards found Verstappen had briefly gone in front of Hamilton when both cars were accelerating and braking but was not in front when the safety car period ended.

Mercedes, accompanied by a team lawyer to a meeting with stewards, argued that Hamilton would have won had the rules on lapped cars been complied with and asked for the result to be changed to the positions after the penultimate lap.

The stewards ruled that it was not appropriate to shorten the race retrospectively.

They recognised that while the rules might not have been applied fully, another article allowed the race director to control the use of the safety car.

© RAW 2021