This photograph taken on March 30, 2023, shows a sign at the entrance of EDF nuclear power plant of Saint-Laurent-des-Eaux, in Saint-Laurent-Nouan, central France. (PHOTO / AFP)

PARIS - A heatwave curbing the availability of cooling water has prompted a production warning from operator EDF for the Saint Alban nuclear power plant on the Rhone river in eastern France for Aug 26 to 27.

Similar warnings have been issued this summer at plants including those at Bugey and Tricastin, which are also on the Rhone.

The Saint Alban production warning likely refers to the plant's second reactor as its first reactor is offline for maintenance until Sept 7.

READ MORE: France's EDF takes 1.3 GW nuclear reactor offline

Authorities in France widened a heatwave red alert for the south of the country on Tuesday. Officials urged some mountain climbers to postpone their activities while grape pickers were advised to start and end their work in the morning to avoid the extreme heat.