An estimated 200,000 women were forced to become sex slaves

Foreign Minister Taro Aso said the resolution was not based on facts.

Sponsored by several members of the US House of Representatives, the proposed text urges Tokyo to formally resolve the issue of so-called "comfort women".

Japan admits its army forced women to be sex slaves during World War II but has rejected compensation claims.

Historians believe at least 200,000 young women captured during World War II were forced to serve in Japanese army brothels.

A large number of the victims - who were known as comfort women - were Korean, but they also included Chinese, Philippine and Indonesian women.

Private fund

Mr Aso described the non-binding resolution, which was introduced in Congress earlier this month, as "extremely regrettable".

"It was not based on objective facts," he told a parliamentary committee meeting.

The resolution calls on Japan's prime minister to "formally acknowledge, apologize and accept historical responsibility" for the comfort women.

The House of Representatives heard last week from three former comfort women who described the rape and torture they endured at the hands of the Japanese soldiers.

Japan acknowledged in 1993 that the imperial army set up and ran brothels for its troops during the war.

The government set up a special fund in 1995, which relies on private donations to provide compensation.

But many former comfort women reject the fund and want formal compensation from the government.