Cabinet's national security committee met urgently on Monday to assess the situation, with Australian air force planes expected to be deployed to Kabul.

Prime Minister Scott Morrison refused to comment on whether the Taliban's lightning advance through Afghanistan had upended rescue plans.

"I can't really talk about operations, but what I can tell you is since April of this year, we've obviously been anticipating this situation," Mr Morrison told the Seven Network.

Since April, Australia has evacuated 430 Afghan employees, and their families, who assisted with the war effort over the past two decades.

Mr Morrison said the government would continue to press forward in evacuations.

The Taliban has taken Kabul after the US withdrew from the country.

The US sent about 3000 extra troops to evacuate embassy staff and others as the capital fell.

The UK also said it was deploying troops to help British nationals and local translators flee.

Australia has joined dozens of countries in issuing a joint statement calling on all parties to "respect and facilitate the safe and orderly departure of foreign nationals and Afghans who wish to leave the country".

"Those in positions of power and authority across Afghanistan bear responsibility, and accountability, for the protection of human life and property, and for the immediate restoration of security and civil order," the statement said.

"The Afghan people deserve to live in safety, security and dignity. We in the international community stand ready to assist them."

Since 2013, Australia has granted visas to 1800 people who worked with its forces out of Afghanistan.

The prime minister said 41 Australians lost their lives fighting for freedom, with the overall mission about tracking down Osama bin Laden and stopping al-Qaeda.

Labor leader Anthony Albanese said the government should have acted quicker to ensure the safety of Afghans who assisted Australia.

"We have a moral obligation to support them and get them here to Australia to safety. There is no question that they remain in great danger," he told reporters in Canberra.

"It is in the interests of Australia's national security to send a message to the world that those who assist us, we will assist them."

Chris Barrie, who was chief of the defence force when Australia entered Afghanistan 20 years ago, said the "ugly truth" was the government left it too late.

The retired admiral said there was not much hope for people who helped Australia and their families.

"It's terrible. I think it's a horrible story," he told ABC radio.

"For all of those people who helped us - God help them."

Amnesty International Australia refugee co-ordinator Graham Thom urged the government to expand its humanitarian intake for people fleeing Afghanistan.

"Australia has an obligation to protect those most at risk including human rights defenders, ethnic minorities and women and children," he said.

Former veterans' affairs minister Darren Chester condemned Nationals colleague Matt Canavan for tweeting: "Does anyone know whether the Taliban will sign up to net zero?"

"This tweet is offensive, disrespectful and totally lacking in any compassion for the 41 brave Australians who lost their lives, the families who grieve for them, the 39,000 Australians who served in this conflict, and the people of Afghanistan," Mr Chester said.

Former deputy prime minister and Nationals leader Michael McCormack labelled Senator Canavan's tweet disappointing, insensitive and unnecessary.

Mr McCormack said comparing climate policy with bloodshed in Kabul was unworthy of an MP.

Australian Associated Press