"Our federations are asking railway workers to strike en masse on Jan. 31 and to hold a meeting on Jan. 31 to decide whether to intensify their action through two consecutive days of strikes on Feb. 7 and Feb. 8," the two unions said in a joint statement.

More than a million people marched through French cities on Jan. 19 to denounce President Emmanuel Macron's plans to raise the retirement age, with a wave of nationwide strikes halting trains, blocking refineries and curbing power generation.

Buoyed by their success, the country's leading trade unions called for a second day of strikes on Jan. 31 in a bid to force Macron and his government to back down on the pension reform plan that would see most people work an extra two years to age 64.

(Reporting by Dominique Vidalon; Editing by Susan Fenton)