The Federal Government has announced it is immediately lifting the freeze on processing the refugee claims of Afghan asylum seekers.

The six-month freeze on processing was due to expire in early October.

Immigration Minister Chris Bowen says all Afghans affected will now have their claims assessed on a case-by-case basis.

"During the last six months, the Department of Immigration and Citizenship has been working to improve its understanding of the situation of asylum seekers from Afghanistan, particularly the situation of Hazaras, who comprise the majority of Afghans seeking asylum in Australia," he said.

"The Government's decision to lift the suspension has been informed by the additional information the department has gathered from a range of sources and close collaboration with the Australian embassy in Kabul."

Mr Bowen says he does not expect the decision to affect the number of boat arrivals.

"We never expected the introduction of the pause in the first place to have an appreciable impact on arrivals - it was not the reason it was done," he said.

"It follows therefore that I don't expect it to have any significant impact when it's lifted."

Opposition immigration spokesman Scott Morrison says the policy was an election-year fix that has resulted in overcrowded detention centres.

"I think this is going to take a long time to clear," he said.

However, Greens Senator Sarah Hanson-Young says the situation in Afghanistan is still very dangerous for many people.

She says the Government needs to deal with the backlog of claims quickly and ensure that enough resources are available.

"The Minister may use those words to talk about further rejections, but it's really important that we assess each individual's claims based on their individual fear of persecution and take on the information from organisations like the UNHCR, who clearly say conditions have not improved," she said.

Mr Bowen says steps are being taken to make sure extra resources are available.

He says it is likely the amount of successful claims will be lower than in the past.

"As a result of the more exhaustive country information, there have been a decrease in the number of primary acceptances of claims from Afghans who are not subject to the processing pause," he said.

"Even taking into consideration the possibility of some of these being overturned at review, the percentage of successful refugee claims is likely to be lower than in the past."

Earlier this year the Government froze refugee applications of asylum seekers from Afghanistan and Sri Lanka.

But the freeze on Sri Lankans was lifted shortly after Prime Minister Julia Gillard came to office.

The Government is expanding the Curtin detention centre and is working to open an asylum seeker processing centre in East Timor.

The Opposition wants the Government to use the centre already in existence on Nauru.