China said yesterday radiation levels remained normal at one of its nuclear power plants and there were no safety concerns, after the station's French operator reported a gas build-up.

"There is no abnormality in the radiation levels around the nuclear power plant, and safety is guaranteed," said foreign ministry spokesman Zhao Lijian.

CNN reported earlier that the US government was assessing a report of a leak at the Taishan nuclear power station in the populous southern Chinese province of Guangdong.

The US broadcaster said the French company, Framatome, warned of an "imminent radiological threat".

Framatome said in a statement to AFP that it is "supporting resolution of a performance issue" at the plant but that according to "the data available, the plant is operating within the safety parameters."

Powered up in 2018, the Taishan plant was the first worldwide to operate a next-generation EPR nuclear reactor -- a pressurised water design that has been subject to years of delays in similar European projects in Britain, France and Finland.