French intelligence officers are 'living in fear' after USB sticks containing their personal details were found in the home of a jihadi knifeman who attacked the force's headquarters last week.
Mickaël Harpon, a 45-year-old IT department worker, stabbed four of his co-workers to death and badly injured a fifth during an attack last Thursday after he began following 'a radical vision of Islam'.
The discovery of the USB drives has led to fears that he could have used his job to extract the names and addresses of intelligence officers and send them other terrorists to carry out follow-up attacks.
The existence of the drives was revealed as Emmanuel Macron attending a ceremony to award the four slain officers the Legion D'honneur, France's highest honour, on Tuesday.
'We will wage an unrelenting fight in the face of Islamist terrorism,' Macron told a ceremony at the police headquarters where the attack took place.
France must develop a 'society of vigilance' in its fight against the 'Hydra' of Islamist militancy, he added.
'The administrative services alone, and all the combined services of the state alone, will not be able to overcome the Islamist "Hydra",' said Macron, during the sombre ceremony held in pouring rain at the police headquarters near Notre Dame Cathedral.
'It's up to the entire nation, which needs to unite, mobilise and be ready to act,' added Macron.
It comes after it was revealed that Harpon - who converted to Islam 18 months ago - expressed extremist sentiments as far back as 2015 but was never properly investigated because his colleagues didn't file a report.
Harpon had defended the massacre of 12 people at the Charlie Hebdo newspaper by two brothers vowing allegiance to Al-Qaeda.
Investigators were continuing to search Harpon's home at Gonesse Tuesday, but sources told local media they are concerned about USB drives containing names and personal data of several dozen of his colleagues at the Préfecture de Police.
They say it is not clear whether the data was extracted surreptitiously or was held as part of Harpon's regular duties, and it is also not clear whether it was passed to third parties.
However, prosecutor Jean-Francois Ricard previously revealed that Harpon was in contact with members of the 'Salafist Islamist movement', raising the prospect that he could have been feeding the information to terrorists.
Yves Lefebvre, a police union spokesman, said: 'It's staggering as well as maddening. How was this person able to get through the net? This is amateurism that needs to be sorted out.
'We can't leave 1,000 intelligence officers at Paris police HQ continue living in such fear and uncertainty.'
Harpon was shot dead following the rampage inside the historic Paris Police Prefecture, next door to Notre Dame Cathedral.
His wife, Iham, was arrested soon afterwards and told detectives that he had ‘heard voices’ and was ‘incoherent and suffered a dementia attack’ the night before.
She has since been released from custody, and has returned to the flat they shared in the Paris suburb of Gonesse.
Harpon and his wife were both registered as profoundly deaf and have two children aged nine and three.
He originally came from the French overseas territory of Martinique, and is believed to have spent time planning the worst loss of French police lives in a single day since World War II.
Harpon had converted to Islam 18 months ago, and his wife is also a Muslim who comes from an Arab background.
The nature of the attack corresponded with similar ones carried out by terrorists affiliated to ISIS and Al-Qaeda.
An investigation as now been launced to see if Harpon was in contact with other Islamists intent on death and destruction.
Colleagues described Harpon as a previously trusted employee who had full security clearance to work in the Prefecture’s IT department.
There have been calls for the resignation of Interior Minister Christophe Castaner, who assisted at today’s ceremony, when the four dead officers received posthumous Legion of Honour medals.