French President Nicolas Sarkozy and his far-right election rival Marine Le Pen traded blows today over claims that all meat in the Paris region is prepared using Islamic halal methods.

Le Pen, trailing both Sarkozy and Socialist frontrunner Francois Hollande ahead of the April-May vote, made the claim at a rally on Saturday and pledged to file a legal complaint for "misrepresentation of products".

Campaigning today in Rungis, home of the main wholesale food market serving the Paris metropolitan area, Sarkozy accused National Front leader Le Pen of getting her facts wrong and creating an artificial controversy.

"There is no controversy here. Every year we consume 200,000 tonnes of meat in the Paris region and 2.5 percent of it is kosher or halal," Sarkozy said.

Halal meat is slaughtered according to Islamic rules that, among other requirements, ban the practice of stunning animals before they are killed.

Some animal welfare campaigners say this is more cruel than standard European practices.

Le Pen, whose party plays on fears of growing Muslim influence, cited a recent public television documentary that said all abattoirs in the greater Paris region use halal methods but do not always label the meat as such.

"It turns out that all the meat distributed in Ile de France is, unbeknownst to the consumer, exclusively halal meat," she said on Saturday. "This is a real deception, the government has been aware of this for months."

On Tuesday she clarified her comments to say that all meat distributed in the region could be suspected of being halal, as without a label "neither you nor I know which is halal and which is not".

"Widespread animal suffering, in violation of French and European law, is not trivial," she said on France Inter radio in response to Sarkozy.

"The fact that a majority of French people are being misled about what they buy is not a trivial controversy," Le Pen said.

Authorities and meat producers also denied Le Pen's claim.

Le Pen's claim is "absolutely false", Interior Minister Claude Gueant said on Sunday, noting that, while there are halal slaughterhouses in the region, their products are clearly marked.

"Veterinary services ensure that abattoirs send halal production to people who want to consume halal meat," he told French media, saying there were "frequent checks to avoid any misrepresentation of products".

Producers said that, while slaughtering in the region was mostly done according to Islamic or Jewish traditions, only about two percent of the meat consumed in the greater Paris area came from the region itself.

Le Pen is struggling to catch up to Sarkozy and Hollande in the election campaign, with polls showing her with between 16 and 20 percent support in what is increasingly looking like a two-horse race.

She inherited the leadership of the National Front last year from her father Jean-Marie, who was known for his anti-immigrant rants and shocked observers by making it to the second round of France's 2002 presidential vote.