The amount of radioactive tritium in wastewater from Chinese nuclear plants, recorded at 13 of the nation's monitoring points in 2021, surpassed the maximum allowable annual amount of the material contained in treated water set to be released from the Fukushima No. 1 plant, according to public data.

Beijing has been opposed to Tokyo's plan to begin releasing treated radioactive water from the crippled Fukushima plant into the sea and has tightened controls on seafood imports from Japan. Tokyo has not taken such measures despite the high level of tritium found in Chinese waters.

Chinese Foreign Ministry spokesman Wang Wenbin has stressed the difference between the Fukushima water and that released by nuclear plants in normal operations, saying no comparison can be drawn between the two as the former "came into direct contact with melted reactor cores."