Australia is planning to send an additional 450 troops to Iraq, Prime Minister John Howard has said.
John Howard said the decision would not be popular
He said the new soldiers would replace a departing contingent of Dutch troops and protect Japanese troops doing humanitarian work in southern Iraq.
Australia already has about 950 troops stationed in and around Iraq.
Prime Minister John Howard, a firm ally of US President George W Bush, said he knew the surprise announcement would be unpopular with many Australians.
But, he said, Australian help was needed to aid reconstruction and prevent insurgents from gaining the upper hand over democracy at a critical juncture in Iraq's history.
The Australian soldiers will help replace troops 1,400 Dutch troops, who are being withdrawn after their government decided against renewing their mission.
In Iraq, the Shia-dominated coalition that won the most votes in last month's election is expected to meet on Tuesday to name its nominee for prime minister, officials say.
The Dawa party's Ibrahim Jaafari is thought to be a favourite for the nomination - but he will face a challenge from Ahmed Chalabi, a former protege of the Pentagon, whose relations with the US soured last year over claims he spied for Iran.
The results of the nomination process, which was suspended to mark the Shia festival of Ashura, were not expected to be known until Wednesday at the earliest, officials said.
Iraq's interim Prime Minister, Iyad Allawi, whose party polled third in the elections, also announced on Monday that he would try for the office of prime minister.
Mr Howard said his country will maintain troops in Iraq as long as they are needed.
"I believe this is the right decision. It will make a significant contribution to the coalition effort. It will make a significant contribution to the rebuilding of Iraq."
He acknowledged it would be an unpopular decision with many at home but said he was responding to requests from Prime Minister Junichiro Koizumi of Japan and the British forces operating in southern Iraq.
"The Japanese element of this is quite crucial because Japan is a major regional partner of Australia," he said.
The leader of the Green party in Australia, Bob Brown, criticised the announcement, accusing Mr Howard of having misled voters during his re-election campaign last year.
"Mr Howard never told voters he would send more Australians to Iraq," Mr Brown said.
The latest deployment will include a cavalry squadron, an infantry company and a team to train local forces and will be ready to leave for Iraq in 10 weeks, Mr Howard said.
He said the two batches of troops would each be sent to Iraq for six months, totalling a one-year deployment.
About 2,000 Australian troops joined in the 2003 US-led invasion of Iraq - a decision that sparked the biggest anti-war protests in the country since the Vietnam war.