Japan on Monday strongly protested against a visit by Dmitry Medvedev, Russian president, to a disputed group of islands seized by Moscow in the closing days of the second world war.

Mr Medvedev’s three-and-a-half hour visit to the four southernmost islands in a 56-island archipelago – known in Japan as the Northern Territories and to Russia as the Southern Kurils – was the first by a Russian or Soviet head of state. The visit threatens to reignite a bitter diplomatic feud over the ownership of the islands.

Seiji Maehara, Japan’s foreign minister, summoned Russia’s ambassador Mikhail Bely to protest at Mr Medvedev’s visit to the islands. Sergei Lavrov, Russia’s foreign minister, condemned the summons as “unacceptable” and insisted the “Russian president [had] visited Russian land” in comments that could intensify the dispute.