US President Barack Obama has telephoned Japan’s new leader Naoto Kan to congratulate him and to pledge co-operation, amid tensions over a US military base on the island of Okinawa.

Tokyo officials said Mr Kan had promised to make “strenuous efforts” to resolve the issue.

Japan’s previous government resigned after failing to deliver an election pledge to move the US base off Okinawa.

Many residents on the island resent the military presence.

Incidents including the rape of a 12-year-old Japanese girl in 1995 by three US servicemen have inflamed public opinion.