Air force troops will base themselves in the United Arab Emirates while waiting for the Afghan capital to become safer.

People swarmed Kabul airport in an attempt to board military flights, with footage showing some falling to their deaths after clinging to planes.

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," the prime minister told reporters in Canberra on Tuesday.

"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."

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

"For Australia, 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.

The prime minister 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.

The prime minister also issued a direct plea to Afghanistan veterans questioning the two-decade mission after the Taliban swept to power after the US withdrawal.

"There is no more decent and good purpose than being willing to serve the country that you love," Mr Morrison said.

"It doesn't mean history's currents always run our way. I wish it did. But, sadly, it doesn't."

Australian Associated Press