In a story that could have sprung from the imagination of the Homeland writing team, it was claimed by a US media outlet at the weekend that one the first targets of US strikes in Syria was a former French intelligence officer who became the highest ranking defector to al-Qaeda.

The report, by McClatchy, makes for astonishing reading: the French officer, whose identity remains a secret, was allegedly working with al-Nusra, al-Qaida's Syrian affiliate, as one of the members of the Khorasan Group, a shadowy unit of top-level terrorist operatives said by the Obama administration to have been dispatched to Syria to plan attacks on the West.

But in France, the existence of an intelligence agent-turned-senior terrorist has been questioned. The country's defense ministry formally denied the allegations in the McClatchy article. The French external intelligence agency, the Direction Générale de la Sécurité Extérieure (DGSE), refused to make any further comment when contacted by VICE News. The French newspaper Le Monde suggested the man may have been bragging about his credentials, citing a defense ministry official as saying: "This Frenchman exists but he is neither a former intelligence agent nor a former military man; to our knowledge he would only have trained with former members of the French military." The foreign ministry said only that it would not comment on "rumors in the press."

The report said the individual "is an explosives expert who fought in Afghanistan and in Syria with Al-Qaeda". VICE News spoke with Alain Chouet, a former department chief in the DGSE, about the man's alleged skills. "Most militants in violent islamist groups are trained — with more or less success — to the use and the deployment of explosives. One more 'specialist' among them won't have a big impact on their capacity to cause trouble and won't add weight to the danger they represent," he said.

The McClatchy article was later backed by ABC News, which cited two US intelligence officials as confirming that the "former French spy" was one of America's primary targets during their airstrikes in Syria. But French experts suggested that the man in question was simply another citizen who had traveled out to join the jihadis. Major General Jean-Claude Allard, research director at the IRIS, a French think tank specialised in strategic and international issues backed that view, telling VICE News: "Double agents were classic during the Cold War, but back then people defected to another strong — and appealing ideology." He cited Bradley Manning as a type of defector in his decision to leak details of US intelligence operations because "he believed in an open world, where everyone could have access to data, it's also a form of ideology."

"I have a hard time believing that a French officer who has been trained by the DGSE would be sensitive to Al Qaeda's repulsive ideology," Allard added.

Chouet suggested that the man in question may not have been of French nationality, but instead had perhaps been a former local asset. He insisted that "no officer or member of the French special services has defected to any jihadist group. That being so, it may not be impossible that a local individual, formerly in contact with French forces in Afghanistan or elsewhere and recruited by them to penetrate enemy lines has changed his mind and turned against his employer. But this hypothesis still needs to be verified and cross-referenced."