The number of jobless in France surged by 0.9 percent in February to a new record of 3.34 million, the labour ministry said on Wednesday.
The number of new jobseekers rose by 31,500 last month, it said, admitting there had been a "marked progression" in unemployment.
The rise is likely to put increased pressure on President Francois Hollande, with the overall number of jobseekers having increased by more than 420,000 since he took office in May 2012.
Hollande's Socialists are struggling to jumpstart France's stagnant economy and are expected to suffer a major poll failure in the second round of municipal elections on Sunday, which could lead to a cabinet reshuffle.
The labour ministry vowed the government would "continue and intensify" its efforts to fight unemployment after the release of the latest figures.
But Jean-Francois Cope, the leader of the centre-right main opposition UMP party, said the figures were "yet another warning shot fired at the government".
He urged voters in Sunday's local elections to "punish" the government for "denying reality and refusing to hear the anger of the French people".