Jordan Bardella, president of France's far-right National Rally party, is under growing pressure as new technical evidence challenges his denials over anti-Semitic messages allegedly sent during his teenage years.

The row over anti-Semitic messages attributed to Bardella intensified on Friday, after investigative website Mediapart published technical evidence it says authenticates private conversations on Facebook's Messenger service dating from 2013.

Bardella has repeatedly denied writing the messages, describing them as fabrications designed to damage his political career. He has announced legal action for defamation as well as forgery and the use of forged documents.

But Mediapart says online conversations obtained from people who knew Bardella at the time were extracted using data held by Facebook parent company Meta, with the process authenticated by a court bailiff.

The controversy escalated further when Justice Minister Gérald Darmanin on Friday accused Bardella of “lying shamelessly” about the messages. Darmanin told radio network RTL that he believed it was “quite obvious” that a National Front activist “aged 17 or 18 who admires [far-right conspiracy theorist and Holocaust denier] Alain Soral... would have been anti-Semitic”. “His strategy of lying to the French people casts enormous doubt on his ability to hold political office," added Darmanin.

Le Pen ally Bardella sues over antisemitism claims, alleges 'total war' Authentication details Mediapart first reported on 28 September that Bardella had allegedly sent anti-Semitic and conspiratorial messages in private Facebook conversations in 2013, when he was 17 and first becoming involved with the National Front – as the National Rally (RN) was known from 1972 to 2018. Bardella rejected the allegations outright and said the messages were fabricated. On Thursday, however, Mediapart published further details of how it says the material was authenticated.

The website said several Facebook Messenger conversations had been provided by two people who knew Bardella during his early political career. Data relating to those conversations was subsequently extracted through Meta and the extraction was certified by a court bailiff.

According to Mediapart, the procedure established the dates of the conversations and showed that they had not subsequently been altered. The outlet also says Meta identified the other participant under the name Jordan Bardella.

Mediapart said biographical details contained in the exchanges also corresponded with Bardella’s life at the time.

Bardella nevertheless maintained his denial after the publication of the new evidence, dismissing the material as “pseudo-evidence” and “crude montages”. He said he would pursue further legal action over what he maintains are forged documents.

France's Le Pen asks Bardella to prepare for 2027 presidential bid Pressure grows on RN The RN has spent years seeking to distance itself from the anti-Semitism associated with the former National Front Darmanin questioned whether the party's parliamentary leader and former president Marine Le Pen could still envisage appointing Bardella as prime minister if she wins the 2027 presidential election The RN, however, has rallied behind its president. Le Pen and other senior party figures have accused Mediapart of waging a politically motivated campaign against Bardella, while he has portrayed the revelations as an attempt to destabilise the party ahead of the presidential vote.

The dispute has also widened into a confrontation between the RN and sections of the French media.

France’s Judicial Press Association on Friday condemned what it described as growing threats and intimidation against journalists, pointing in particular to Le Pen’s remark that Mediapart reporters should wear “a Kevlar suit".