The latest attempt by South Korea and the United States to narrow their gap on sharing the cost of keeping U.S. troops here ended without a clear breakthrough but both sides agreed to meet again next week, Seoul government sources said Saturday.

The talks, the ninth in their series since last year, opened in Seoul earlier in the day after a two-day break that followed two days of negotiations. Their goal is to rewrite the so-called special measure agreement (SMA) that sets the amount of financial contributions South Korea will make toward keeping U.S. troops on its soil in the next five years.

South Korean officials have earlier said they will seek to conclude their negotiations as soon as possible as the current SMA is set to expire at the end of the year.

A government official, however, said the sides have yet to reach an agreement.

"The two sides plan to resume their talks early next week after a short break," said the official, speaking on condition of anonymity.

The South Korea-U.S. defense treaty, under which the U.S. stations its soldiers in South Korea to guard against North Korean threats, had originally put the burden of bankrolling U.S. defense activities on the U.S. side.

However, South Korea currently covers more than 40 percent of the cost of some 28,000 U.S. troops stationed here under the latest SMA signed five years ago.

The size of South Korea's contributions remains the major sticking point as of now.

Seoul wants to keep its current yearly payment level of about 869.5 billion won ($825.7 million), while Washington is pushing to increase the amount to around 1 trillion won, citing mounting security threats from North Korea. (Yonhap News)