Prime Minister Scott Morrison is optimistic Australia’s evacuation mission in Afghanistan will succeed, despite chaos at Kabul airport delaying the effort.

Mr Morrison confirmed on Tuesday that Australia’s rescue mission was underway but conceded the government would not be able to help all Afghans who worked with and supported Australian troops.

Air force troops will base themselves in the United Arab Emirates while waiting for the Afghan capital to become safer – although it is not known when that will be.

On Monday and earlier on Tuesday, footage emerged of people swarming Kabul airport in an attempt to board military flights, with footage showing some falling to their deaths after clinging to planes.

Mr Morrison said he was “optimistic” that the rescue mission would go ahead, but the priority was ensuring it was done safely.

“Right now, I’m focused on the very desperate situation that exists in Kabul right now, making sure that the operations that we are mounting are successful,” he said in Canberra.

Cabinet’s national security committee is meeting daily to discuss the dire situation and Australia’s rescue efforts for citizens and visa holders.

The mission will include more than 250 Australian defence personnel supporting three RAAF aircraft in a US-led operation.

“I do remain optimistic about those operations,” Mr Morrison said.

“That’s why we continue to authorise and proceed with our plans to ensure we can get done what we hope to get done in the days ahead.”

This photo obtained by media organisation Defense One shows more than 600 Afghans crowded onto a US plane as it leaves Kabul. Photo: Defense One

Mr Morrison said he understood many Australian veterans of the two-decade war in Afghanistan were worried about locals they had worked with.

“The scenes from Kabul have been absolutely heartbreaking. It’s a sobering day for everyone and particularly those who have given so much over the past 20 years and most notably those 41 who were lost,” he said.

“I want you to know that we will continue to do everything we can for those who have with us, as we have to this day. But I want to talk openly to veterans that despite our best efforts, I know that support won‘t reach all that it should.

“We wish it were different.”

Defence Minister Peter Dutton said the tragic scenes made it incredibly difficult for Australia’s mission until US forces secured the airport.

“We won’t be landing aircraft into the airport until it’s safe to do so,” he told Sky News on Tuesday.

There are more than 130 Australians working for the United Nations, non-government organisations and elsewhere still in Afghanistan, which is now under Taliban control.

Immigration Minister Alex Hawke confirmed no Afghan visa holder in Australia would be sent home while the situation remained dire.

Mr Morrison refused to commit to offering paths to permanent residency or citizenship, but insisted there were no plans to send people into danger.

Opposition Leader Anthony Albanese said the idea that minority groups like the Hazara community would ever return wasn’t realistic.

“We need to give them the certainty of Australian citizenship on a permanent basis, rather than some pretence that somehow their circumstances are temporary,” he said.

Mr Morrison didn’t rule out a special intake of refugees, similar to the 12,000 people granted asylum from Syria in 2015.

But he said his immediate focus was on making sure the Australian mission was successful given the desperate situation in Kabul.

Since April, 430 Afghan employees, as well as their families, have been brought to Australia with 670 visas granted.

Mr Albanese said Labor had called for people who helped Australian troops to be evacuated for months.

Mr Dutton said the exact number of locally engaged employees was hard to determine with some taking up asylum offers in other parts of the world.

But he warned that anyone intelligence showed worked for al-Qaeda or the Taliban, as well as Australia, would not be granted a visa.

-with AAP