WASHINGTON -- The United States is looking for "further compromise" from South Korea in their defense cost-sharing negotiations, the State Department said Monday amid a prolonged impasse in talks.

The comment comes after US President Donald Trump said last week that he rejected South Korea's offer because he felt the Asian ally should pay more for the stationing of 28,500 American troops in the country.

"The United States remains committed to concluding a mutually acceptable agreement. Our longstanding view is that the Republic of Korea can and should contribute more of its fair share," a department spokesperson told Yonhap News Agency on condition of anonymity.

"During the course of negotiations, we have adjusted and compromised. We have shown significant flexibility in recent weeks in order to reach a mutually acceptable agreement. We're looking for further compromise from the Republic of Korea Government as well," he added.

An earlier news report said that Trump rejected a South Korean offer to increase its contribution by at least 13 percent from last year.

The two sides have been negotiating a new Special Measures Agreement (SMA) on defense cost-sharing amid US demands for a significant hike in Seoul's contribution.

Under the previous one-year SMA, which lapsed at the end of last year, South Korea agreed to pay $870 million.

More than 4,000 South Korean employees with US Forces Korea have been placed on unpaid leave since April 1 due to the absence of a new SMA to cover their salaries.

A government source in Seoul said Sunday that South Korea is pushing to pay the workers first by deducting the amount from its eventual payment to the US under a new SMA.

The spokesperson said that as a matter of policy, the department will not publicly confirm or comment on South Korean proposals that are being addressed between allies in diplomatic channels. (Yonhap)