Investigating agencies now claim at least two of the attackers, involved in the six coordinated attacks in Paris that killed at least 129 people on Friday, entered Europe on boats carrying refugees from Syria.
The security agencies have identified one of the bombers as Ahmed Almuhamed, 25, who blew himself up at the Bataclan concert hall, where at least 80 people were killed in the attack claimed to have been carried out by Islamic State (Isis) militants, reported The Daily Mail.
According to Serbian newspaper Blic, Almuhamed entered Europe along with another Paris bomber. The report said the two landed on the Greek island of Leros on 3 October.
A Greek minister also confirmed on Saturday night that one of the suicide bombers identified by his Syrian passport was Ahmed Almuhamed, reported DebkaFile. His identity was confirmed by his fingerprint, said the report.
Amid what is being seen as a failure of the French intelligence agencies, reports for long have been doing rounds that Isis is sending fighters to Europe along with refugees.
A report back in September had said Isis has been able to send as many as 4,000 radicalised fighers into Europe â€” hidden among innocent refugees.
A smuggler had told Buzzfeed the Isis operatives were asked to infiltrae into Europe to carry out a "large-scale" revenge attack against the West in retaliation for the US-led coalition bombings in Syria-Iraq against Isis.
Coincidentally, the report had emerged just as France carried out its first airstrike against Isis in Syria. Earlier this month, France also announced it was sending in the massive Charles de Gaulle aircraft carrier to support operations against Isis in Syria and Iraq, Reuters had reported.