Former prime minister John Howard believes Australia has a moral obligation to help the Afghan workers, especially as the Taliban advances throughout the country.

"We're doing everything we can," Mr Morrison told ABC radio on Friday.

At least 1400 Afghan workers and their families who worked with the defence and foreign affairs departments have been brought to Australia over recent years.

"Hundreds are in that process right now," the prime minister said.

"We're doing that as fast and as safely as we can."

He said there was a "high level of urgency" within the government to get the job done.

"It's obviously an environment in which it is difficult to operate, people would appreciate that."

Some protection visa requests have been rejected because the Afghan workers were subcontractors, and not directly employed by the Australian government.

Mr Morrison said Afghan subcontractors could apply through Australia's humanitarian visa stream, rather than one dedicated to locally engaged workers.

"We work through both channels," he said.

Mr Howard, who sent Australians to fight and die in Afghanistan, doesn't want the subcontracted locals they fought alongside left behind to meet the same fate.

He has piled pressure on the federal government to grant protection visas for Afghan subcontractors who fear for their lives under resurgent Taliban rule.

The government is being urged to fast-track applications from interpreters, contractors and security guards as Australia's longest war draws to a close.

Mr Howard said the nation has an ethical duty to provide safe haven for Afghans who aided their cause.

"It was a moral obligation that we shamefully disregarded many years ago when we pulled out of Vietnam," he told SBS News.

"I do not want to see a repetition of that failure in relation to Afghanistan."

Mr Howard, who doesn't regret following the US to war in Afghanistan, said the subcontractor technicality should not be used to keep those in danger from safety.

"I don't think it's something that should turn on some narrow legalism," he said.

"If a group of people gave help to Australians such that their lives and that of those immediately around them are in danger we have a moral obligation to help them."

Taliban fighters have been advancing across the country in recent weeks as Australia and the United States end two decades of involvement in Afghanistan.

Australia has granted more than 230 visas to Afghans workers and their family members since April 15.

Australian Associated Press