Australia announced in 2003 it would cooperate with the United States on missile defence, amid controversial plans by the Bush administration to establish a protective shield against possible missile attack.

The idea, reminiscent of former president Ronald Reagan's 'Star Wars' initiative, has been widely criticised as unlikely to prove 100 percent effective and liable to stir up tension, particularly with China.

In a brief statement, the Department of Defence gave only the scarcest of details.

"A delegation from the United States Department of Defense is visiting Australia to continue discussions with the Australian government about missile defence cooperation," it said.

"The visit is at the working level and follows on from the signing of the missile defence memorandum of understanding in July 2004.

"The talks are exploring possible areas of cooperation on missile defence, concentrating on research and development. The government will consider any proposals once they are fully developed."

Despite its support, Australia has not announced any financial contribution to the program and its support is seen as largely rhetorical, like its low-scale contribution to the war in Iraq.

According to media reports, Washington is interested in Australia's Jindalee over-the-horizon radar technology, which protects Australia's northern approaches, and wants to know if it could be used to track incoming missiles.