Australian Prime Minister John Howard has said his country will commit troops to any American-led war against Iraq.
There is strong opposition to war in Australia
Just hours after his announcement the Australian Government ordered all Iraqi diplomats to leave the country by the end of the week.
"This course of action is clearly a logical and prudent step in
a situation where Australia is engaged in military action against
Iraq," said Foreign Minister Alexander Downer.
He said the Iraqi diplomats had to be out of Australia no later than midnight on Sunday, 23 March.
In an audacious protest against their government's policy, peace campaigners clambered onto the sails of the Sydney Opera House and painted "No War"
in large red letters.
Other anti-war protests were planned
Australia has already sent about 2,000 troops to the Gulf, including elite SAS commandos, along with fighter jets and warships.
Mr Howard said the cabinet decided to commit forces to the coalition against Iraq after he had discussed the situation by phone with US President George Bush.
The BBC's Phil Mercer in Sydney says Mr Howard - one of the staunchest allies of President George Bush - has the united support of his cabinet colleagues.
In a televised address, the prime minister said Australian forces in the Gulf would be placed "as part of any US-led coalition operation that may take place in the future".
Howard said committing troops was in Australia's interest
He said such action "has a sound legal basis in the resolutions of the [United Nations] Security Council that have already been passed".
His comments came hours after the US, UK and Spain withdrew a draft second resolution which would have paved the way for military action if Saddam Hussein failed to disarm.
The UN is split over whether existing resolutions authorise the use of force against Iraq.
There is strong opposition in Australia to a war with Iraq, with thousands of protesters demonstrating against military action over the past few weeks.
Mr Howard said he was "very conscious" of public opinion, but the government had "taken a decision which it genuinely believes is in the medium and longer term interests of this country".
He said the number of Australian forces in the Gulf would not be increased.
Opposition Labour Party leader Simon Crean earlier warned that committing Australian troops would increase the risk of terror attacks.
The decision to join any US-led war will be debated in the Australian parliament on Tuesday, but will not be put to a vote.