France security forces escort a woman from a building in Lyon following the terror attack on Friday. Credit:AFP Salhi confessed to the grisly crime earlier on Sunday and has also given "details about the circumstances" surrounding the killing, according to sources. He left the police headquarters in Lyon in a van escorted by nine unmarked cars en route to the capital. Investigators discovered on Saturday that the married father-of-three had sent a photo of himself and the severed head via the WhatsApp messaging service to a number in Canada. But officials warned the Canadian number might be a relay number and the intended recipient could be anywhere in the world.

Herve Cornara's severed head was found lashed to the gates of the factory near two flags. Credit:AFP Hundreds of French citizens have left for Iraq or Syria to wage jihad and Prime Minister Manuel Valls said earlier on Sunday that 1800 people in France were "linked" in some way to the Islamist cause. After several hours of silence, Salhi began to open up to investigators about the assault. His wife and sister, who were both taken into custody on Friday, have been released. Salhi rammed his van into the US-owned Air Products factory near Lyon on Friday in what President Francois Hollande said was a "terrorist" attack designed to blow up the whole building.

He was overpowered by a firefighter as he was trying to prise open a bottle of acetone in an apparent suicidal bid to destroy the factory. Police then made the shocking discovery of the severed head of Salhi's boss, 54-year-old Herve Cornara, tied to the gates of the factory near two flags on which were written the Muslim profession of faith. Valls told French television on Sunday that the world was engaged in a "war against terrorism". "We cannot lose this war because it's fundamentally a war of civilisation. It's our society, our civilisation that we are defending," Valls said. It's also emerged that Salhi and Cornara may have quarrelled just two days before the killing after Salhi dropped a crate of expensive materials.

Friday's attack came on a day of bloodshed on three continents that saw 38 people mown down on a Tunisian beach and 26 killed in a suicide attack in a Kuwait mosque. The Islamic State extremist group has claimed responsibility for those two attacks but no group has said it carried out the French operation. Sources close to the investigation said Salhi was radicalised more than a decade ago after contact with Muslim convert Frederic Jean Salvi - known as "Ali" - who is suspected of preparing attacks in Indonesia with al-Qaeda militants. Interior Minister Bernard Cazeneuve said on Friday Salhi had been investigated for links to radical Salafists in Lyon, but was not known to have participated in terrorist activities and did not have a criminal record. AFP