The suspected Islamist who attempted to blow up a French chemical plant on Friday has admitted killing his manager beforehand, a source close to the investigation said on Sunday, as police linked the suspect to a militant now in Syria.

Yassin Salhi, 35, told detectives he had killed Hervé Cornara in a parking area before arriving at the plant in Saint Quentin-Fallavier, 30 km (20 miles) south of Lyon, where he tried in vain to cause a major explosion.

Police found the 54-year-old victim's decapitated body and head, framed by Islamic inscriptions, at the plant, which is owned by the U.S. firm Air Products. There were no other casualties.