Le Pen comes under attack

French far-right leader Marine Le Pen came under assault from all sides in a presidential election debate that provided a test of centrist Emmanuel Macron's ambitions to be leader.

Le Pen and Macron, the two leading candidates according to opinion polls with just over a month to go before voting begins, traded barbs in the televised debate watched by nearly 10 million people on Monday.

Commentators agreed, however, that neither landed a knockout blow.

Macron, the 39-year-old former economy minister who is untested at the ballot box, had the most to lose in his first major debate -- and the first ever of the main candidates before the first round of voting -- but he held his ground.

It was Le Pen, 48, who was repeatedly thrust onto the defensive as Macron, the conservative nominee Francois Fillon, the Socialist Party's Benoit Hamon and fifth-placed leftist radical Jean-Luc Melenchon all tore into her protectionist, anti-immigration programme.

Former frontrunner Fillon, who is trying to refocus attention on his politics after becoming embroiled in a host of scandals, said Le Pen's proposal to ditch the euro and bring back the franc would cause "economic and social chaos".

She accused him of "scaremongering".

Le Pen is hoping to ride the wave of populism that led British voters to choose to quit the EU and swept Donald Trump to power in the US, though the failure of the Dutch far-right leader Geert Wilders's party to perform more strongly in his country's general election last week was a setback to her hopes.

While polls show that Le Pen would finish in the top two at the first round on April 23, they also show that she would be handily beaten in the May 7 runoff by either Macron or Fillon.

Le Pen was playing to her support base when she accused Macron of being "in favour" of the burkini, a full-body swimsuit worn by some Muslim women that was banned by several coastal French towns last year.

He bridled at the suggestion, accusing her of "lying" by "twisting the truth" and seeking to "divide the French" over the issue.

A total of 11 candidates, spanning the spectrum from the Trotskyist left to the far right, are running for president. Six other candidates currently with low polling numbers were excluded from Monday's debate but are expected to take part in the next one.