China has reiterated its opposition to Japan's release of treated and diluted water from the Fukushima Daiichi nuclear plant, following reports of harassment targeting Japanese-related facilities in China.

Chinese Foreign Ministry spokesperson Wang Wenbin was asked by a reporter during a regular briefing on Monday about China's response to the reported cases of harassment.

Wang said China consistently guarantees the safety and rights of foreign nationals in the country based on law.

He said he wants to make it clear that Japan ignored strong doubts and opposition by the international community and unilaterally discharged the water. He said China demands that Japan immediately halt the release of "nuclear-contaminated water."

Another reporter asked about reports that some Japanese businesses and institutions are receiving volumes of abusive phone calls apparently from China. Wang replied he has not grasped the situation and declined to comment.

Wang also referred to the postponement of a visit to China by the head of Japan's junior coalition party Komeito, Yamaguchi Natsuo, that had been scheduled to start on Monday. The spokesperson said the visit has been postponed through talks in view of current relations between the two countries.

Wang said China attaches great importance to dialogue and exchange with Komeito and hopes both sides will work to improve ties between the two countries.