Poland's government says it has taken the "very difficult decision" to extend its military deployment in Iraq until the end of 2006.
The Polish deployment in Iraq is not popular at home
The new conservative government's decision reverses the previous leftist administration's plan to pull troops out in early 2006.
Poland, a staunch ally of the US, has about 1,500 troops stationed in Iraq.
It is the fifth biggest foreign contingent in Iraq, after the US, Britain, South Korea and Italy.
Among other US European allies, Bulgaria, Hungary and Ukraine have already opted to withdraw their forces.
The last Ukrainian forces serving in Iraq left on Tuesday, the defence ministry said.
Their withdrawal coincided with that of the remaining 130 Bulgarian troops.
Polish Prime Minister Kazimierz Marcinkiewicz, elected in October's parliamentary elections, has asked the Polish president to keep his country's forces there for another year.
"This is a very difficult decision, but we take into consideration the fact that the mandate of UN stabilisation forces has been extended to the whole of 2006 and, secondly, strong requests of Iraqi authorities that we stay there," he said.
The force would be cut to 900 in March and its focus shifted to training Iraqi troops, Polish Deputy Defence Minister Stanislaw Koziej said.
In September 2003, after the March invasion, the US put Poland in charge of an international force in south-central Iraq, including the Poles.
Opinion polls show the deployment is unpopular at home, with a majority of Poles wanting the soldiers to pull out.
President Yushchenko saw Ukraine's last Iraq unit end its mission
The violence in Iraq has killed 17 Polish soldiers, the Associated Press reports.
The BBC's Adam Easton in Warsaw says many Poles feel the country has got very little in return for its commitment.
But most Polish politicians believe the country has won prestige by commanding a multinational force in Iraq, he says.
During Mr Marcinkiewicz's visit to Iraq last week, he estimated it would take another 12 months before Iraqi forces could take over the Polish zone.
The decision to stay has to be ratified by the new Polish president, Lech Kaczynski. He is a close political ally of the government, so that looks set to be a formality, our correspondent says.
Earlier this week Ukraine's President Viktor Yushchenko paid a surprise visit to Iraq and inspected the last Ukrainian unit to be withdrawn.
Ukraine had contributed 1,650 troops to the US-led coalition - the largest non-Nato contingent there.
The Ukrainian defence ministry has said 50 military instructors will stay in Iraq to train local forces.
MAIN INTERNATIONAL CONTINGENTS IN IRAQ
US: 155,000 troops
South Korea: 3,500
Source: Reuters/Global Security; as at Dec 2005