Russia's prosecutor general has banned a group campaigning for Japanese sovereignty over four disputed islands seized by the Soviet Union at the end of World War II, amid rising tensions between Moscow and Tokyo.

The group — known as the League of Residents of Chishima and Habomai Islands and called Chishima Renmei — organized annual trips to the islands by their former Japanese residents and their descendants, thousands of whom were forced to leave after the war.

The four southernmost islands of the chain — all of which are administered by Russia — are claimed by Japan as its Northern Territories. The dispute has prevented the two sides from ever formally signing a peace treaty to end the war.