TOKYO (AFP) - Japan's Prime Minister Shinzo Abe struck a conciliatory tone on Friday at an unusually low-key annual rally demanding the return of islands occupied by Russia, hours before he left for the Winter Olympics in Sochi.

Mr Abe will attend the opening ceremony of the Games in southern Russia later on Friday where he will also meet President Vladimir Putin, the latest step in an increasingly close working relationship.

"I will hold the fifth summit with President Putin tomorrow," Mr Abe, who took power in December 2012, told the annual gathering demanding the return of the Northern Territories, four islands and some islets Japan claims but Russia administers as the Southern Kurils.

"I am resolved to address the negotiation patiently so as to reach the final goal of solving the issue of the Northern Territories," he said, calling it "the most concerning matter left between Japan and Russia".

The two nations have not signed a peace treaty because of the territorial dispute which began when Soviet troops seized the islands in the last gasps of World War II.

The gathering in Tokyo is usually a rambunctious affair, with nationalist politicians and activists making hot-headed demands for the immediate return of islands that were home to a few hundred Japanese until foreign troops arrived.

But its timing this year, just hours ahead of Mr Abe's attendance at the Sochi Olympics opening ceremony, meant the rhetoric was toned down.

"As I have agreed with President Putin, I have to say that it has been abnormal that a peace treaty has not been signed between Japan and Russia even 68 years after the war," Abe said.

"We need to tackle it, with the government and the people all together, so as to move forward the negotiations with Russia." Observers say the spat is unlikely to be resolved on this visit, although progress is being made.

Some expect that a final settlement will see Russia retain the two larger islands, while the two smaller ones are returned to Japan - a solution Moscow first offered in 1956.

Any movement on the issue would mark a big achievement for Mr Abe amid territorial disputes with both China and South Korea over two separate archipelagos.

The row with Beijing is particularly nasty and frequently involves paramilitary stand-offs, with some commentators warning it could degenerate into armed confrontation that might drag the United States in.