Emmanuel Macron is set to win the first round of the French general election in four weeks time, BVA pollsters said, becoming the latest survey team to put the independent centrist ahead of far-right leader Marine Le Pen for the first time.

The BVA poll did not give a second round prediction, but most that have done so in recent months show Macron easily beating the National Front leader in the second-round run-off due to take place between the top two scorers on May 7.

Macron will get 26 percent of the first round vote, up one percentage point from his showing a week ago, BVA said. It put Le Pen on 25 per cent, down one point.

Scandal-hit third-placed candidate Francois Fillon slipped 2.5 percentage points on the week to 17 per cent.

That showing follows a TV interview on Thursday night in which the conservative and erstwhile favourite accused President Francois Hollande of leading a smear campaign against him.

The poll was conducted between Wednesday and Friday.

It also showed far left candidate Jean-Luc Melenchon gaining ground, up 2 points from a week earlier to 14 per cent.

Melenchon was considered by voters to have done well in the first TV debate between the main candidates that took place on Monday evening. Macron was also seen to have performed well in the debate.