China's Ministry of Ecology and Environment on Wednesday identified several issues with Japan's plan to monitor the treated radioactive water from Fukushima nuclear plant before discharging it into the sea.

The ministry said there is a time delay between the monitoring results and the discharge, so there is a chance that the radioactive water that failed to meet the standard could be released directly into the sea.

It also pointed out that mixing nuclear wastewater before the monitoring may dilute the radioactive content in the water, producing inaccurate test results.

"There should be transparent, open, long-term international monitoring rather than just the Japan-led observation for a show," the ministry added.

China has conducted several marine environment observations for radiation in the past two years. "We have already made plans and will send out alerts once we find anything usual," the ministry said.

The ministry also disputed the rumor claiming Chinese nuclear plants discharged tritium 6.5 times than that in the radioactive water from the Fukushima plant.

"The contaminated radioactive water from Fukushima plant is fundamentally distinct from the regular discharge released by other countries," said the ministry.

"The sources are different, the types of radionuclides are different, and the processing difficulty is different."

The nuclear-contaminated water from Fukushima is the cooling water injected into the melted and damaged core after the accident as well as the groundwater and rainwater that infiltrated into the reactor.

While the wastewater generated by the normal operation of nuclear power plants mainly comes from process drainage, ground drainage and contains a small amount of fission nuclides. This practice is strictly in line with international standards and the water is treated and discharged with the best available technology in an organized manner after strict monitoring and compliance, said the ministry, asserting that "emissions are far below the limit."

"We must be vigilant about the attempt to confuse the concepts of regular discharge from nuclear plants and Fukushima's contaminated radioactive water," it warned.

"We're opposed to releasing contaminated radioactive water, not regular discharge."