(Adds details, more unplanned outages at nuclear reactors)
PARIS, March 13 (Reuters) - A one-day strike in the French gas and electricity sector has cut power production by 4.2 gigawatts (GW), French utility EDF and grid operator RTE said on Monday.
The strike, expected to last from Monday evening until 2000 GMT on Tuesday, was called by French energy sector workers to protest against wage freezes.
EDF said on its website that hydropower production was cut by 280 megawatts (MW), while its 535 MW Porcheville 3 fuel-powered generator and the 580 MW Havre 4 generator, reported unplanned outages after workers downed tools.
Separately, RTE said that the unplanned outages caused by the strike had reduced output at seven of France's 58 nuclear reactors, cutting electricity output from the reactors by nearly 3 GW.
The power generation plants are expected to resume full production by 2100 GMT on Tuesday, RTE said. (Reporting by Bate Felix; editing by Gareth Jones, G CROSSE)