Scott Morrison has warned the most dangerous part of Australia's rescue mission in Afghanistan lies ahead after another 650 people were evacuated.
The five latest flights take the total of people airlifted from Kabul as part of Australia's efforts to almost 1700 since the operation began last week.
The prime minister told coalition colleagues on Tuesday the evacuation mission was being conducted in one of the most dangerous parts of the world.
"The hardest and most difficult and dangerous part is ahead of us still - getting out the remaining people and making sure we can evacuate our own people safely," Mr Morrison said.
"Those Australians on the ground are saving lives. Lives that would otherwise be shattered and destroyed if we weren't able to operate those operations so successfully to date."
He said Australia would continue evacuation flights if the United States decided to extend the withdrawal deadline past August 31.
"I've made no assumptions about the Taliban - we know their form," Mr Morrison told the Nine Network.
"We've been going like we won't be able to get another flight in the next day, so we've been trying to make every flight as successful as possible."
The prime minister said the mission would continue for as long as it could.
"If that deadline is able to be pushed out, we've made that clear to the United States that we would support that," Mr Morrison said.
"But in the meantime, we'll just keep getting on with the job."
Labor's foreign affairs spokeswoman Penny Wong said there were dreadful consequences for people left behind under the Taliban.
"The hard reality is the government acted too late," she told a caucus meeting.
"Helping those who help us is both an ethical responsibility and a national security priority."
Deputy Prime Minister Barnaby Joyce said it was not a perfect situation but he would rather be an Australian trying to leave Kabul than from many other countries.
"We will hear about the person left behind. We'll hear about the atrocious actions of terrorism. We will hear about the person who was killed," he told partyroom colleagues.
Britain plans to use an emergency G7 summit to lobby US President Joe Biden to extend the presence of American troops beyond the August 31 deadline.
A second repatriation flight of evacuees arrived in Melbourne from the United Arab Emirates on Monday, taking the total brought to Australia to 271.
Independent MP Andrew Wilkie, who spent more than two decades in the military, continues to push for Australia to join other democracies in requiring parliament to approve declarations of war.
"History shows decisions to go to war are not something any government, nor prime minister, can be trusted with," he said.
The prime minister said the government supported retaining the status quo around executive powers set out in the constitution.
Mr Wilkie said the Howard, Rudd, Gillard, Abbott, Turnbull and Morrison governments owned the Afghanistan tragedy.
© AAP 2021