The Chinese government will take all necessary measures to safeguard food safety and the health of the Chinese people, China's Foreign Ministry said on Thursday after Japan started releasing nuclear-contaminated wastewater from the crippled Fukushima Daiichi Nuclear Power Plant into the Pacific Ocean.

China firmly opposes and strongly condemns the move and has lodged solemn representations with the Japanese side to demand that it cease the wrongful act, the ministry said in a statement shortly after the release process started on Thursday.

"The disposal of the Fukushima nuclear-contaminated water is a major issue about nuclear safety. Its impact goes beyond Japan's borders, and the issue is by no means a private matter for Japan," according to the statement. "To forcibly start the ocean discharge is an extremely selfish and irresponsible act in disregard of the global public interest."

China warned that there could be a man-made secondary disaster for the local people and the whole world if Japan chooses to dump the water into the ocean just to serve Japan's selfish interests.

Japan failed to prove that the ocean discharge is safe and harmless to the marine environment and people's health and that the monitoring plan is sound and effective, the ministry noted.

By doing so, Japan has turned itself into a saboteur of the ecological system and polluter of the global marine environment, the statement said.

Japan is infringing upon people's rights to health, development and a healthy environment, which violates its moral responsibilities and obligations under international law, it added.