Japan's longest-serving prime minister - a Nobel Peace laureate - asked the US in 1965 to deploy nuclear weapons against China if war broke out between the Asian rivals, according to newly declassified government files obtained by Kyodo news agency.

During his first trip to Washington as the Japanese leader, Eisaku Sato told then-US Defense Secretary Robert McNamara that American military forces could launch a nuclear attack on China by sea if needed, Kyodo said yesterday.

Under its post-World War II constitution, Japan renounces war as a sovereign right and prohibits the use of force in international conflicts.