Russia has handed over the remains of suspected Japanese soldiers who died defending an island in the Northern Territories from a Soviet invasion after Japan's surrender in World War II.

The 27 sets of remains were found on Shumshu Island, now a part of Russia's Kuril Islands chain. They were cremated this week and handed over to a Japanese official on Wednesday in Yuzhno-Sakhalinsk, the capital of Sakhalin Island.

The remains were found during research on Shumshu by the Russian military and a group studying wartime history. The work began last year.

The remains were cremated Monday in the Sakhalin town of Smirnykh and were on Wednesday handed to a Japanese welfare ministry official by the government of the Sakhalin region. Among them were four sets of remains of suspected Japanese soldiers found on Sakhalin.

Japanese House of Councillors member Toshiei Mizuochi, head of Nippon Izoku Kai, an association representing the families of people who died in World War II, is set to bring the remains to Japan on Thursday.

Japan surrendered on August 15, 1945. Shumshu Island, the second northernmost of what was called the Chishima Island group, was invaded by Soviet forces before dawn on Aug. 18 of that year.

The invasion sparked a major battle with Japanese troops while Tokyo was in the process of demobilization following its acceptance of the Potsdam Declaration, which demanded Japan's unconditional surrender.

About 3,000 Soviet and 350 Japanese troops are believed to have died by the time a cease-fire agreement was reached on Aug. 23 of that year, but the exact number of casualties remains unknown.