The table showed availability reduced by 5 gigawatts (GW) at seven nuclear reactors and down by another 340 megawatts (MW) at hydropower plants.

Workers in sectors including transport, education and energy across France are due to take part in the strike on Thursday, with major protest marches expected in Paris and other cities.

Unions are up in arms over plans by President Emmanuel Macron's government to raise the retirement age by two years to 64 in order to keep the pension system out of the red.

(Reporting by Forrest Crellin; writing by Leigh Thomas; Editing by Leslie Adler and Marguerita Choy)