French Prime Minister Manuel Valls has announced he is going to fight to become the left-wing candidate in next year's presidential election.

Mr Valls is quitting his job to enter the race for the Socialist party.

It follows the decision of sitting Socialist President Francois Hollande not to run for a second term.

Valls faces a serious challenge from Marine Le Pen, leader of the anti-EU, anti-immigrant National Front Party.

Centre-right candidate Francois Fillon is also a serious contender.