TOKYO - POLICE in Japan said on Tuesday they were probing apparent explosions in the south-west of the country, including one at the office of a group promoting Sino-Japanese relations.

Employees of the local office of the Japan-China Friendship Association in southwestern Tokushima prefecture discovered damage on Tuesday after returning from a three-day holiday weekend, police said. No one was injured.

'We set up an investigation into the case after an official at the association found that the door and part of the ceiling at the office were damaged,' said a police spokesman.

Police were investigating if the case was related to similar damage found on Monday at the local office of Buddhist group Soka Gakkai, the power base for the New Komeito party, part of Japan's ruling coalition.

Relations between Japan and China have long been strained due partly to Japan's militarism until the end of World War II.

However, in recent months leaders of the two countries have been working to improve relations, which hit rock bottom during the 2001-2006 tenure of Japanese premier Junichiro Koizumi. -- AFP