The source said the EDF trade unions calling for the December 5 strike included the CGT, Force Ouvriere (FO) and the Sud trade union.

The December strike is gearing up to be a major confrontation between President Emmanuel Macron's government and those opposed to his plans for pension reforms.

(Reporting by Sophie Louet; Editing by Sudip Kar-Gupta/Benoit Van Overstraeten)