A Chinese nuclear company has deliberately released gas from a power plant into the atmosphere within authorised limits, as it seeks to fix an issue at the facility, its French partner said Monday.

"We are not in a scenario of an accident with a melting core," an EDF spokesman said at a press conference, seeking to ease concerns after a CNN report of a potential leak at the Taishan Nuclear Power Plant in southern Guangdong province.

EDF reported earlier a build-up of noble gases in one of the two reactors' primary circuits, which is part of the cooling system.

Noble gases are elements which have low chemical reactivity -- in this case it was xenon and krypton.

The gas was released after the coating on some fuel rods had deteriorated, said the spokesman, who asked not to be named.

The gases were collected and treated, and their release into the atmosphere was "normal" and "in accordance with regulations", he said.

"We are not talking about contamination, we are talking about controlled emissions," the spokesman said.