Security has been stepped up around political rallies and meetings in France amid heightened fears of a terror attack with just four days of campaigning until the first round of the fiercely contested presidential election.

The five main candidates have vowed to continue campaigning as it emerged that France’s police and intelligence agencies spent several weeks tracking the two men arrested on Tuesday and suspected of plotting an “imminent and violent attack” in the run-up to Sunday’s vote.

Officials say they are still investigating the men’s possible targets, but claim they were seeking to “have an impact in this [electoral] period” and had amassed an arsenal of weapons and bomb-making equipment, including 3kg of homemade explosive found in the flat where they were staying.



It was reported on Wednesday that Paris’ anti-terror court had opened a preliminary investigation into suspect Mahiedine Merabet, 29, on 5 April, after receiving a tip-off from British intelligence that he had tried to make contact with Islamic State (Isis) in order to send them a video expressing his support for the terrorist group.

Clement Baur, left, and Mahiedine Merabet. Photograph: Handout/AFP/Getty Images

The previous day Merabet had sent his identity card and bank card to the police station near his last known residence in Roubaix, northern France, along with a note, explaining: “Because of you, I can’t use them. I’ll hand myself in soon and we’ll talk. What do you, the police, want with me. Leave me alone, I’ve nothing to say to you.”



Merabet was already on the security service’s radar after a December 2016 raid on the Roubaix flat, where an Isis flag and propaganda was reportedly found. He disappeared and his flatmate gave a false identity. It was only after talking to Merabet’s family in Marseille that police realised the second man at the flat was Clément Baur, 23, a Muslim convert. The two met in prison where they shared a cell in 2015.

Search warrants were put out for the pair, both on the Fiche-S, a list of those suspected of being a threat to national security.

Police stepped up the search on 12 April after intercepting a video, reportedly filmed in a Marseille apartment, that showed Merabet with an Uzi submachine gun, ammunition, an Isis flag and photographs of children allegedly killed in French and American bombing raids in Syria. The film’s title was: “The Law of Retaliation”, a police source told French journalists.



A copy of Le Monde newspaper with a front-page picture of the presidential candidate François Fillon and dated 16 March was also filmed.



The five main presidential candidates were immediately alerted and advised to increase security, both personal and around their political meetings.



The Paris prosecutor François Molins said the Tuesday the arrests of Merabet and Baur had been the result of “international cooperation”, but admitted investigators were trying to establish their planned targets.



As France’s interior minister announced “exceptional” security measures for the presidential campaign, the five main candidates responded by downplaying the threat and continuing electioneering.



The Socialist party candidate, Benoît Hamon, who polls place last out of the leading five, said he refused to make it a “campaign issue”, the conservative Fillon, currently in joint third place with the hard-left candidate Jean-Luc Mélenchon, said the threat would not make him “back down a single squared centimetre”.



A spokesperson for Marine Le Pen, currently heading the polls with the independent centrist Emmanuel Macron, said the arrests hours before Le Pen’s rally in Marseilles was “perhaps not a coincidence”.



With one-third of French voters still undecided and many others threatening to abstain, the margin of error in the opinion polls mean any permutation of the four main candidates – Macron, Le Pen, Mélenchon, Fillon – is possible in a second round runoff next month between the top two candidates.

