French investigative site says antisemitic messages tied to Jordan Bardella, Le Pen's ally

A French investigative journalism website said Thursday it had been able to authenticate antisemitic messages from 2013 attributed to far-right presidential candidate Marine Le Pen's de facto deputy.

The allegations against Jordan Bardella come just seven months out from the election where voters will choose a replacement for President Emmanuel Macron, with Le Pen leading opinion polls.

Bardella, 31, has strongly denied writing the messages and on Thursday said he would file a legal case againstthe Mediapart outlet for defamation, as well as "forgery and use of forgeries". 

Mediapart published screenshots of the antisemitic messages Bardella is said to have sent to another person on Facebook's Messenger chat platform in 2013. 

Read moreStill the same far right? Le Pen's National Rally denies fresh anti-Semitism claims

The outlet said biographical details revealed in the conversations prove that it was the real Bardella: a mother born in Italy, mention of an interview he gave to Le Parisien in 2013, and failing the entrance exam for the prestigious Sciences Po university.

"Extracting the conversation makes it possible to date it, to certify that this conversation was not altered after the fact, and to confirm that the person on the other end is listed by Meta/Facebook under the name Jordan Bardella," Mediapart said.

"Analysing its content makes it possible to verify that it is indeed the real Jordan Bardella."

Bardella denounced what he called Mediapart's "pseudo-evidence" as "crude fabrications, obscure and easily manipulated screenshots, repeating revolting remarks that I obviously never made".

Le Pen hits back 

Bardella is expected to become prime minister if Le Pen wins next year's election, and the affair threatens to damage her "de-demonisation" project to make her National Rally (RN) party more palatable to voters. 

Read moreFrance's Le Pen vows to 'counterattack' after top ally Bardella hit by anti-Semitism claims

She is riding high in the polls, and the 58-year-old has strongly defended Bardella, who has helped the party make inroads among younger voters.

Rival presidential candidate and former prime minister Edouard Philippe said that in light of the new evidencefrom Mediapart "it is virtually established" that Bardella made remarks "of an obviously and scandalously antisemitic nature".

Mediapart on Monday published the contested messages, dating back to when Bardella was a young party activist.

Le Pen has voiced her "total confidence" in Bardella and denounced a "total war" against her party as she makes a fourth attempt to win the presidency.

A poll on Monday suggested she would easily lead the first round of next year's election and go on to defeat any challenger in the second round run-off.