South Korea's government is to submit to parliament a proposal to withdraw a third of the country's troops in Iraq, according to media reports.
The proposed withdrawal was not mentioned in talks on Thursday
The proposal came to light a day after US President George W Bush praised South Korea for its Iraq contribution.
The White House, which seemed surprised by the proposal, insisted there had been no official confirmation.
South Korea's contingent of 3,600 troops is the largest in Iraq after those of allies the US and Britain.
South Korea's defence ministry detailed the proposal to withdraw about 1,000 troops from Iraq to the ruling Uri Party, and the government will submit a motion on the issue to the National Assembly, according to Yonhap news agency.
"[Given] the stable security condition in Iraq and the recent development involving multinational troops there, we judge it possible to partly reduce the Zaytun unit," Defence Minister Yoon Kwang-woong was quoted as saying.
Zaytun refers to the contingent of South Korean troops stationed in the Kurdish-controlled town of Irbil in northern Iraq.
Analysts say that while Irbil's security situation is much better than Baghdad's, it has still suffered periodic violence, and six people were reportedly killed there earlier this week.
The White House appeared taken aback by the proposal.
"They have not informed the United States government of that," said National Security Council spokesman Frederick Jones.
The timing of the proposal caused surprise, since it came just a day after President Roh Moo-hyun held talks with his US counterpart, George W Bush.
"The issue was not raised" during Thursday's talks between Mr Roh and Mr Bush, Mr Jones said. "Just the opposite."
The South Korean public is sharply divided over the issue of the deployment of its troops in Iraq.
The government is keen to bolster its ties with the US, which it sees as an important counterbalance to the threat from North Korea.