SEOUL • South Korea and the United States have signed a formal agreement under which the former will pay 8.2 per cent more to host American troops.

The two sides agreed last Friday that the signing of the Special Measures Agreement, a result of tough negotiations, reflects their robust alliance, reported Korean news agency Yonhap.

"This now becomes... one of the foundations of the alliance, and something that the alliance will build upon to become stronger and greater," South Korean Foreign Minister Kang Kyung-wha was quoted as telling Washington's top envoy in Seoul, Mr Harry Harris, after the signing ceremony in the South Korean capital.

Last month, South Korea agreed to pay 1.04 trillion won (S$1.25 billion) this year for the operations of the 28,500-strong US Forces Korea, up from 960 billion won the previous year.

Mr Harris said the accord represents the significance of the alliance, reported Yonhap.

"It underscores the importance and the ironclad nature of our alliance between our two great nations that have worked together and represents the sacrifices of Koreans and Americans over the decades," he said.

The increase in costs is part of the Donald Trump administration's efforts to make countries hosting US troops pay more. The South Korean government will submit the accord to the National Assembly this week for ratification.