Sources close to Japan-China relations say a senior official of the Chinese Communist Party's international department is set to visit Japan around May 27.

The official is Liu Jianchao, head of the Chinese Communist Party's international department.

The sources said arrangements were being made for Liu to meet with Japanese politicians.

They include Yamaguchi Natsuo, leader of Komeito, the ruling Liberal Democratic Party's junior coalition partner, and LDP Secretary General Motegi Toshimitsu.

Liu is also apparently seeking meetings with senior officials of the Japanese government.

The visit is expected to help improve soured ties between Japan and China.

Outstanding issues include China's opposition to Japan's release of treated water from the Fukushima Daiichi nuclear power plant into the sea and Chinese authorities detaining Japanese nationals on suspicion of spying.