Jordan Bardella, president of France's hard-right National Rally (RN), has threatened legal action for libel after a report alleged he made antisemitic comments as a young activist, denouncing the claims as part of a "total war" aimed at destabilising his party.

The investigative website Mediapart published what it described as the result of "several months" of investigation into "dozens of written conversations" Bardella allegedly had in 2013, when he was 17 or 18 years old.

Among the statements Mediapart alleges he made are: "All the banks are owned by Jews"; "The Jew has to dominate other people, crush them and rob them"; and "What they want is a new world order dominated by Israel, with of course Jerusalem as its capital."

Mediapart did not produce screen-grabs of any of the alleged remarks. It said it had "independently authenticated" the conversations, which came from "a bigger documentary base corroborated by witness statements."

Bardella, 31, denied the allegations, calling them a fabrication aimed at derailing the RN's bid for power. "Everything is going to be done to destabilise the campaign," he told a French television channel on Monday. "Either Mediapart is running this operation itself, or it is being manipulated by interested parties. Of course I have instructed my lawyer to sue for libel."

RN presidential candidate Marine Le Pen expressed full confidence in Bardella, saying the alleged remarks "seem so weird that they can only be a forgery — one of those dirty tricks for which Mediapart appears to hold the secret."

Bardella is widely regarded as a likely prime minister should Le Pen win the presidential election, scheduled for 2027. He has been a central figure in Le Pen's long-running effort to shed the party's far-right image and present the RN as an electable mainstream force.

RN deputy Jean-Philippe Tanguy suggested the allegations originated with former party members who had been expelled years ago over their own antisemitic views. "From what I know, it is the antisemitic rabble that were so bravely purged by Marine Le Pen. At the start of the 2010s, they were numerous and well-organised, but they were defeated. These people have always had it in for us."

Leftwing politicians called on Bardella to resign. The head of the Jewish umbrella organisation Crif, Yonathan Arfi, said the alleged comments "were an illustration of the limits of the RN's clean-up act."

Mediapart, which describes itself as a leftwing outlet, said the alleged remarks contradict the RN's public repositioning on antisemitism. Under Le Pen, the party has made sustained efforts to distance itself from the French far right's antisemitic roots. Bardella was the first senior RN figure to be invited to Israel, attending a conference on antisemitism last year.

The controversy comes at a sensitive moment for the party. The RN received a boost on Sunday when partial Senate elections produced enough seats for the party to form an official group in the upper house of parliament for the first time.

Opinion polls also show the party riding high ahead of the 2027 presidential vote. A survey by Toluna-Harris published this week showed Le Pen winning the decisive second round against all likely rivals. According to the poll, she would take 35 to 36 percent of the vote in the first round, then defeat radical-left candidate Jean-Luc Mélenchon with 69 percent in a run-off. The same poll showed her beating the most popular centrist candidate, Edouard Philippe, with 57 percent.