South Korea and the United States have discussed delaying a scheduled reduction in the number of US troops based on the peninsula, a Seoul military official said Wednesday.

"Nothing has been decided but there were discussions on this issue," the official told AFP on condition of anonymity.

"This is in line with the new government's move to strengthen ties."

Media reports said the two sides are close to agreement on delaying this year's scheduled pullout of 3,500 troops, because of North Korea's continuing military threat.

The Korea Herald, quoting an unidentified defence ministry official, said an accord may be finalised at this week's Camp David summit between US President George W. Bush and new South Korean President Lee Myung-Bak.

The US has based troops in the South since the 1950-53 Korean War to deter any North Korean attack.

Under a worldwide US troop realignment plan, the two countries agreed in 2004 to cut the number from 37,500 to 25,000 by the end of this year. There are currently 28,500 members of the US military in South Korea.

North Korea test-fired long-range missiles and staged a nuclear test in 2006. It has since reached an international deal to shut down its nuclear programme.

But cross-border tensions have risen since Lee's conservative government took office in February and pledged a firmer line with the North, angering Pyongyang.

"North Korea is still a threat due to its nuclear programme and long-range missiles. Fewer US soldiers on the peninsula harm the joint readiness of the two countries," Dong-A Ilbo newspaper quoted a military source as saying.

The paper said a pause in the troop withdrawal would also mean no reduction in the number of F-16 fighter planes and Apache gunships based in South Korea.

Reports said the Seoul government has been reluctant to raise the issue publicly since it may give Washington more leverage in upcoming negotiations on how to split the bill for the deployment.

South Korea currently pays about 43 percent of the cost, or 720 billion won (732 million dollars) a year. The US wants a 50-50 split.

The two allies will start talks later this year to decide on cost-sharing for the next two years.