Japan has started sending seawater into an underwater tunnel built to release nuclear-contaminated water into the ocean from the crippled Fukushima Daiichi Nuclear Power Plant, local media reported on Tuesday. 

Tokyo Electric Power Company (TEPCO), the plant's operator, said the process started on Monday afternoon, according to the national broadcaster NHK. 

The Chinese embassy in Japan released a statement on Monday accounting the hazards of discharging nuclear-contaminated water from Fukushima Daiichi Nuclear Power Plant. 

The statement referenced data from a report issued by TEPCO, saying that the radioactive elements in the marine fish caught in the harbor of the plant far exceed safety levels for human consumption.

In particular, the statistics released show that the content of Cs-137, a radioactive element that is a common byproduct in nuclear reactors, is 180 times that of the standard maximum stipulated in Japan's food safety law. 

There are more than 60 radionuclides, including tritium, carbon-14, cobalt-60, strontium-90 and iodine-129, in the nuclear-contaminated water, according to the statement. 

Some long-lived nuclides may spread with ocean currents and result in a bioconcentration effect, which will increase the total amount of radionuclides in the environment and cause unpredictable hazards to the marine ecosystem and human health, it said, adding that the discharge will last as long as 30 years or even longer. 

The statement noted that research has shown that it takes less than 57 days for the radionuclides to spread across most of the Pacific Ocean and to the world oceans after 10 years. 

Opposition from the international society continues 

Opposition against Japan's decision on nuclear wastewater has been continuing. 

A spontaneous protest was held in front of the headquarters of TEPCO in Tokyo on Wednesday evening. The protesters said that the discharge of nuclear-contaminated water in the ocean is a highly irresponsible act.

On the same day, Green Korea United, an environmental group, also staged a protest in front of the Japanese embassy in Seoul, calling the discharge an "international crime" that will transfer the risk of further pollution to the world through the seas, China Media Group (CMG) reported.

There have been concerns about the impact of the discharge on fishing, agriculture and tourism. 

"I think that the release of radioactive wastewater will affect me and any human's daily life. This thing will also impact fishing, agriculture, tourism and other industries because it has a negative impact on not just humans but also nature," a Malaysian resident told CMG in May. 

Sumio Konno, former employee of the Fukushima Daiichi Nuclear Power Plant, strongly voiced his anger at the Japanese government's plan, warning of the serious economic and health implications of such a move which he said will "haunt our children's future."

"Most people are against the plan of discharging wastewater into the sea, as it will affect fisheries and agriculture. People also think that if the wastewater goes into the sea, they will never have delicious sea fish again, and the fish will have no buyers. If people suspect the fish to be poisonous, they will not want to eat them," Konno told CMG in an interview in May. 

"Japan is not left with no other choice in the disposal of the Fukushima nuclear-contaminated water. Yet the Japanese government unilaterally decided to simply dump the nuclear-contaminated water into the ocean without fully studying and assessing other disposal options," said a Chinese Foreign Ministry spokesperson at a press briefing in Beijing on Wednesday. 

"Such conduct of impairing the common interests of all mankind for its selfish interest cannot convince the people at home and abroad but is only to disgrace Japan itself, harm the people of neighboring countries and Pacific island countries, and further discredit Japan in the international community," the spokesperson added.

(With input from Xinhua)