A leaked document from France's anti-terror unit revealed that the country is already host to 8,250 radical Islamists and that even its own security forces are infiltrated with radicalised officers, including police officers who have broadcast Muslim chants while on patrol and openly refused to protect synagogues.

The memo said the number of radical Islamists increased by half in just one year. Between 2012 and 2015, 17 officers were reportedly radicalised by jihadi groups with at least one police officer refusing to observe a minute of silence to commemorate the victims of a terrorist attack.

French authorities have reportedly expressed deep worry of a security breach "far more serious than merely social media post'' as these alleged officers are routinely armed and have access to databases packed with sensitive information.

In addition, the police were alerted to a policewoman who incited terrorism on Facebook, and called her police uniform a "filthy rag of the Republic" while wiping her hands on it.

She also wrote on her Facebook page: "Masked attack led by Zionist cowards... They need to be killed" shortly after the attacks on Charlie Hebdo and the Hypercacher kosher supermarket in Vincennes last January, which left 17 people dead.

Thibaut de Montbrial, a counter-terrorism specialist and head of the centre for Internal Security Studies, told French newspaper Le Figaro: "Someone in uniform atttacks another person, wearing the same uniform ... In France, such a scenario is not impossible. Security forces must keep this risk in mind.''

The French army is also reportedly concerned about a rise in young recruits showing signs of radicalisation.

Last week, a retired French soldier was arrested after landing in Morocco with a suitcase packed with kitchen knives, a machete and a gas cylinder, reports said.

Manuel Broustail, a military veteran who converted to Islam, has been under surveillance by French security agencies since he was discharged in 2014. He was previously placed under house arrest in the aftermath of the Paris terror attacks.

The Express has reported that the Paris police headquarters is now "planning weekly review of officers' behaviour in a bid to spot the first signs of extremism, including monitoring changes in clothing, sick leave or theft of supplies."