President Francois Hollande shocked France on Thursday, December 1 by announcing he would not seek a second term next year, acknowledging his deep unpopularity and making way for another leftist candidate to take on conservative Francois Fillon and far-right leader Marine Le Pen, Reuters reports.

The surprise announcement - effectively an admission that by running again he would hurt his Socialist party's chances - marks the first time since France's fifth Republic was created in 1958 that an incumbent president has not sought a second mandate.

"I am aware today of the risk that going down a route that would not gather sufficient support would entail, so I have decided not to be a candidate in the presidential election," a sombre-looking Hollande said in a televised address.

Dogged by high unemployment, Hollande is the least popular president in French polling history, yet his closest aides had consistently said he would run.

Hollande's retreat makes it likely that his prime minister, Manuel Valls, will throw his hat in the ring to take part in the Socialist primaries in January, Reuters says.

"In doing this, I'm facing my responsibilities," said Hollande. Black-suited and stony-faced, he called for all people with a "progressive" political viewpoint to unite. He also warned about the rise of populism and the far right.

"I do not want France to be exposed to risks which would cost it dear, and even threaten its unity, its cohesion, its social balance," he said.