Marine Le Pen is leading the race for the French presidency, the latest opinion polls show.

The far-right leader of the National Front has between 25 to 26 per cent of support, ahead of Republican candidate Francois Fillon, who has between 23 to 25 per cent.

However, the Ipsos Sopra Steria poll for Le Monde only shows voting intentions in the first round of the presidential election.

Marine Le Pen is leading the race for the French presidency, the latest opinion polls show

Fillon is widely expected to defeat Le Pen in the second round, which is between the final two candidates.

The poll indicates that Independent candidate Emmanuel Macron is in third place, on between 17 percent and 20 percent, while Jean-Luc Melenchon from the Left Party is in fourth place on 14 to 15 percent of the vote.

The ruling Socialist Party still trails well behind in fifth place, between five to seven points behind Melenchon.

All the predicted scores varied according to which Socialist candidate emerges from the primaries, with former prime minister Manuel Valls as the frontrunner.

He will contest the first round of the Socialist primaries on Sunday with former economy minister Arnaud Montebourg, and Benoit Hamon, an ex-education minister.

A second round is due to take place on January 29 between the top two scoring candidates.

Republican candidate Francois Fillon is behind on 23 to 25 per cent but is widely expected to defeat Le Pen in the second round

The first round of the election itself is due to take place on April 23, with the top two scoring candidates also going through to a second, run-off round.

Most polls predicting a run-off result have shown Fillon beating Le Pen in that second round, although some scenarios have predicted a contest that Macron would win.

Independent candidate Macron threw down a direct challenge to France's existing political parties on Thursday by announcing he would field candidates in all constituencies in June's parliamentary elections.

Macron is a centrist whose rise in opinion polls is worrying left-wing and right-wing candidates in the presidential race.

Independent Emmanuel Macron is in third place, on between 17 percent and 20 percent