The plan, being considered by the Australian Defence Force, follows an upsurge in pirate activity in which Somali pirates have seized cargo ships and demanded millions of dollars in ransoms for their release.

The United States has expressed a strong desire for Australian involvement in a new multinational counter-piracy taskforce, which was formed on January 1.

Defence head Air Chief Marshal Angus Houston said yesterday that taking on the pirates was a possible role for an Australian warship since the country had ended its long-running mission guarding Iraq's offshore oil terminals at the top of the Persian Gulf.

The Australian warship would serve in what's called Task Force 151, alongside US, British and other nations' warships.

HMAS Parramatta, now in the final weeks of its six-month deployment to the Persian Gulf, is part of the US-led Task Force 152 engaged in patrolling the central gulf area.

Air Chief Marshal Houston said the defence force was considering all the options for future deployment.

''Task Force 152 is one. There is also the possibility of perhaps going further and getting involved in some of the important counter-piracy work that is coming on in the north Indian Ocean,'' he told sailors aboard the Anzac class frigate HMAS Parramatta yesterday.

''That is something we will be looking at quite carefully in the months ahead, developing a proposal for government's consideration.''

Australian warships have operated almost constantly in the Persian Gulf since before the 1991 Gulf War, initially enforcing United Nations sanctions against the former Iraqi regime and more recently guarding Iraq's two vital offshore oil terminals.

After the negotiation of a memorandum of understanding with the Iraqi Government, the Australian Government decided the time was right to end the security role in the northern gulf.