PARIS, April 19 (Reuters) - A nationwide strike called by unions to protest against the government's planned liberalisation reforms has reduced French electricity generation at nuclear and coal-fired plants by over 4 gigawatts on Thursday, showed data from grid operator RTE.

RTE said output had been reduced to zero at the Cordemais 4 and 5 coal-fired units with an installed capacity of 580 megawatts each.

Production was also cut at five nuclear reactors.

France's far-left CGT trade union had called for a walkout at power generation sites and had said it will carry out targeted power cuts during the protest. (Reporting by Bate Felix; Editing by Sudip Kar-Gupta )