Russian Foreign Minister Sergey Lavrov denied on Wednesday that Moscow was imposing an ultimatum on Japan in talks to end a decadeslong territorial dispute, but called on Tokyo to recognize the results of World War II.

Japan is seeking a peace deal with Russia it hopes will end a dispute over islands off Hokkaido captured by Soviet troops in the last days of World War II, a disagreement that has long soured bilateral relations.

Prime Minister Shinzo Abe has launched a diplomatic campaign to strike a deal with Moscow, but Russia says Tokyo must recognize Russian sovereignty over the islands before progress can be made in peace talks.

"These are not pre-conditions, it's just an effort to understand why Japan is the only country in the world which cannot say: 'I accept the results of World War II in their entirety,'" Lavrov told a news conference.

Foreign Minister Taro Kono held talks about the territorial dispute with Lavrov in Moscow on Monday and Abe is set to have discussions with Russian President Vladimir Putin on Jan. 22.

Lavrov has said a Russian desire to normalize relations with Tokyo meant it agreed to step up talks about the territorial dispute and the peace deal, but that significant differences remain between the two sides.

Opinion polls show most Russians oppose handing back the islands to Japan, and Russian nationalists plan to stage a demonstration in Moscow this weekend calling on the Kremlin to keep the territory.