SYDNEY - Three Australian prisoners forced to dig coal for a company owned by Japanese Prime Minister Taro Aso's family during World War II are seeking compensation, according to a report Friday.

John Hall, Joe Coombs and Arthur Gigger sent a joint letter to Aso requesting a personal apology for their ill treatment and for refusing to concede the truth of their plight, The Australian newspaper reported.

The conservative Aso hails from a wealthy family, and admitted under pressure in parliament earlier this year that prisoners held by Japan during World War II dug coal for his family's mining company.

"Taking these steps will be the honourable road for you, your family's company, and Japan," the men wrote, according to The Australian.

The men were among 300 Allied POWs, including 197 Australians, who were drafted into labour at the Aso Mining Company's Yoshikuma coal mine in the southern prefecture of Fukuoka.

The men said they were forced down regularly collapsing mine shafts for 12 hours at a time, in stifling heat wearing only loin cloths, and were beaten if they failed to meet quotas.

"Some (compensation) would be nice," Coombs, 88, told the paper. "They made money out of the mines, we did the work. It's the least we deserve."

Yukihisa Fujita, leader of the main opposition Democratic Party of Japan (DPJ), has urged Aso to apologise and promised to make "considerable progress" on war compensation if elected in polls due before September.

In December Japan's welfare ministry released documents showing that 300 British, Dutch and Australian prisoners of war worked at the company's mine.

The documents said two Australian POWs died during the three-month period but the ministry blacked out the causes of their deaths as well as other personal information, citing privacy.