Chinese former slave laborers and relatives of others who have since died submitted a petition Friday to Prime Minister Junichiro Koizumi, demanding an official apology and compensation for their wartime labor at the Hanaoka coal mine in Odate, Akita Prefecture.

The group includes 16 former workers at the mine, which is known for the bloody suppression of a 1945 uprising by Chinese laborers that left more than 100 dead, and 21 relatives of deceased laborers.

They collected more than 80,000 petition signatures in China before coming to Japan.

After submitting the petition, they staged a sit-in outside the Diet building to protest the government's reluctance to admit responsibility for wartime slave labor.

The Chinese were invited to Japan to attend a memorial service marking the 59th anniversary of the riot, held Wednesday in Odate, under a compensatory program run by a fund set up by construction giant Kajima Corp.

The general contractor's predecessor, Kajima-gumi, used to run the mine.

Nearly 40,000 Chinese were rounded up and taken to Japan in 1944 and 1945 and sent to 135 sites nationwide to work as slaves. Of these, 986 were sent to the Hanaoka mine, nearly half of whom died due to severe working conditions and torture meted out as punishment for the uprising.

In an out-of-court settlement, Kajima agreed to create the fund in 2000 to compensate the victims, with some 500,000 yen being dispersed to each of the 450 former workers and relatives of the deceased.

It also gave special scholarships to 400 families with young children.

In a news conference Friday, Li Shaohai, an 82-year-old survivor who heads a group of Hanaoka victims, argued that the slave labor was a joint crime perpetrated by Japan's government, its military and its corporations.