SEOUL, South Korea - South Korea, one of the closest U.S. allies in Iraq, is preparing a plan to pull its 1,300 troops out of the country, a Defense Ministry official said Friday.

The South Korean presence in Iraq began in 2003 with a 600-strong contingent. The country sent 3,000 more troops the following year at Washington's request, making it the United States' biggest coalition partner after Britain.

However, the troop levels have since gradually declined amid rising public opposition to the mission. Calls for withdrawing the troops reached their peak when Islamic insurgents beheaded a South Korean civilian working in Iraq in June 2004, after Seoul rejected demands to withdraw its forces. South Korea now has about 1,300 troops in Iraq.

"We're drawing up a mission termination plan and will submit it to the National Assembly in June," the official said on condition of anonymity, citing policy. The official declined to give details.

In December, the National Assembly approved the extension of the deployment for another year, on the condition that the government draws up a troop pullout plan this year.

Iraqi Prime Minister Nouri al-Maliki, on a visit to Seoul, said in an interview with the Hangyoreh newspaper that he believes South Korea could start withdrawing its troops "in the near future."