Prime Minister Shinzo Abe said that signing a Japan-Russia peace treaty, delayed for decades by the row over Russian-held islands off Hokkaido, will require a "relationship of trust" between himself and President Vladimir Putin.

Abe's remarks at a news conference in Buenos Aires on Monday came just a day after Putin had poured cold water on Japanese hopes of quickly concluding a World War II peace treaty.

Putin said such an agreement is "not an easy path," reiterating that the contentious islands, seized from Japan by the Soviet Union at the end of World War II in 1945, fall under Russian sovereignty.