TOKYO (AP) _ Rokuro Saito spent his first winter in Stalin's Siberia laying railroad track 10 to 12 hours a day, digging holes in the frozen ground for shelter at night, watching his compatriots die of cold and starvation.

He has spent the rest of his life seeking an apology. He may finally get one this week from Russian President Boris Yeltsin, who arrived in Tokyo on Monday.

Saito is one of some 600,000 Japanese soldiers captured by Soviet troops in the last days of World War II and kept as unpaid labor in Russia's Far East for years after the war ended.

In the decades since, efforts by the former POWs to get redress have been overshadowed by Tokyo's demands that several small islands seized by Soviet troops after the war be returned.

Those demands have chilled relations between the two countries and kept them from signing a peace treaty to formally end their World War II hostilities.

It is widely felt here that Yeltsin, whose government replaced the Soviet regime responsible for the internment, is in a position to clearly acknowledge Stalin's excesses. In lieu of politically risky territorial concessions, he is expected to take the less controversial step of making an apology to the POWs.

''A clear apology is important to us, and I think Yeltsin is in a good position to offer one,'' Saito, head of the 70,000-member Japan POW Association, said by telephone from his home in northern Japan. ''It is just a first step, but it is a very important one.''

Japan and the Soviet Union technically closed the door on the issue of reparations to the POWs and their survivors in a joint declaration signed in 1956.

That document only acknowledged the deaths of 3,957 internees, though historians now believe as many as 60,000 might have died.

Saito and other former POWs have reopened the compensation issue with a suit demanding that the Japanese government compensate them for their labor. Japan's Supreme Court is hearing the case, and Saito said he expects a ruling next year.

''Our problem has been ignored by the government and the public for too long,'' he said. ''But there are 200,000 surviving POWs and we are getting old. We can't be ignored forever.''

British and Dutch held as war prisoners by Japan in World War II also are demanding compensation for their sufferings. In their case, too, Japan says postwar agreements closed the compensation question.

Taken prisoner in Harbin, China, on Aug. 18, 1945, three days after Japan's surrender, Saito spent the next four years and nine months with about 40,000 other Japanese POWs near the Siberian town of Irkutsk. He was 21 years old when he was taken prisoner.

''It was a very lonely, barren place,'' he said. ''About 4,000 of my fellow prisoners died in the first year alone. They couldn't adjust to working and sleeping out in the cold or to the diet of black bread and cabbage.''

Saito has returned to Russia many times since his release, and has helped erect monuments at the graveyards of Japanese POWs who died before coming home.

He said he was encouraged by former Soviet President Mikhail Gorbachev's decision to stop over at one of those graveyards before coming to Tokyo two years ago.

Gorbachev, the only Soviet leader to visit Japan, called the simple wreath- laying ceremony an ''act of reconciliation.''

He also expressed his condolences to the families of POWs who ''died far from their homeland.'' But he did not acknowledge Soviet responsibility for wrongdoing, or mention the issue in the more formal setting of a speech to Parliament.