The United States says it might have to build a special export version of the Raptor fighter plane if the aircraft is sold to Australia.

At alliance talks in Canberra yesterday, the Australian Government expressed interest in buying the United States' F-22, which is described as the top combat plane in the world.

All overseas sales of the jets are currently banned by an Act of Congress.

Yesterday Australian Defence Minister Joel Fitzgibbon said he would write to the US Government asking for the US to lift the ban.

US Defence Secretary Robert Gates says the Pentagon should have looked at the legal ban more closely, because Japan asked to buy the Raptor last year.

Dr Gates says he will consider Australia's request and whether an export version of the Raptor would have to be created.

"[We would have to look at] whether there would have to be design changes and so on," he said.

"Given the importance that our Australian friends attach to it, it's an issue I intend to pursue when I get back, first of all in terms of conversations with our own people in the Department of Defence and also with the Secretary of State."

Mr Fitzgibbon recently launched a review of the controversial $6 billion contract to buy F/A-18F Super Hornet fighter jets, which was signed off on by his predecessor, Brendan Nelson.