TOKYO - RUSSIA'S upper house speaker voiced hope on Thursday for progress in a longstanding territorial row with Japan ahead of an expected visit to Tokyo by powerful Prime Minister Vladimir Putin.

Mr Sergey Mironov, the speaker of the Federation Council and a close Putin ally, said Japan and Russia should strengthen economic and cultural ties to help resolve the dispute over four Kuril Islands.

'We must take every chance to deepen trust between our two countries in order to make progress. It is through that that we shall solve a very difficult problem,' Mr Mironov told reporters in Tokyo.

'Russia's approach is very logical and justified,' he said.

Mr Mironov met on Wednesday with Prime Minister Taro Aso to help prepare for Mr Putin's visit expected later this year. No date has been set, he said.

Mr Putin's expected visit 'will give a powerful incentive to overall Russo-Japanese relations", he said, adding that several unspecified bilateral agreements are expected to be signed at that time.

Japan, a close US ally, has never formally ended World War II with Russia due to the dispute over the four islands off Japan's northern coast.

Soviet troops seized the islands days after Tokyo's surrender in 1945 and expelled their Japanese residents.

Diplomacy has repeatedly failed to resolve the row. Japan demands the return of all four islands, which it called the Northern Territories. -- AFP