TOKYO (AFP) - Japanese Prime Minister Shinzo Abe on Saturday pledged to resolve a row with Russia over an island chain claimed by both nations and sign a bilateral peace treaty delayed since WWII.

Relations between Moscow and Tokyo have been strained for decades over of the status of four Pacific islands near Japan's north coast, known as the Southern Kurils in Russia and the Northern Territories in Japan.

"As I have agreed with (Russian President Vladimir) Putin, it is abnormal that Japan and Russia have not concluded a peace treaty," Abe told an annual gathering in Tokyo to demand the return of the territories.

"I am determined to continue working tenaciously on this issue... in full accordance with the government's fundamental policy of resolving the issue... and concluding a peace treaty with Russia."

Soviet troops seized the islands just after Japan surrendered in World War II and Tokyo says the islands are now illegally occupied by Russia.

The seven-decade dispute over their ownership has kept Moscow and Tokyo from signing a post-war peace treaty.

Foreign Minister Fumio Kishida told the same rally issue is the biggest stumbling block hindering relations between the two nations.

Japan holds a demonstration on February 7 every year to mark a 1855 bilateral treaty that set its border with Russia.