Intelligence obtained by Western security agencies before the November 13 Paris attacks indicated as many as 60 ISIL terrorists had been deployed by the group to Europe to carry out attacks on five cities.

Intelligence obtained by Western security agencies before the November 13 Paris attacks indicated as many as 60 terrorists of the so-called 'Islamic State of Iraq and the Levant' (ISIL) takfiri group had been deployed by the group to Europe to carry out attacks on five cities and had already reached European soil, CNN news network reported citing a senior European counterterrorism source.

The intelligence indicated the target cities included Paris, London, Berlin and a major population center in Belgium, according to the source.

It also indicated Abu Mohammed al-Adnani, the head of ISIL' external operations efforts, was the key figure behind the ambitious plan, the source said. There was no indication the plan was to attack the cities simultaneously.

The source cautioned the threat stream was based on intelligence which was fragmentary and difficult to verify, and it was too vague to act on.

In the year before the Paris attacks, Adnani had threatened the European countries supporting the anti-ISIL coalition in a series of audio messages, making specific references to France and Belgium.

And in January 2015, Belgian police broke up a major ISIS plot in Belgium coordinated by Abdelhamid Abaaoud, who later became the ringleader of the Paris attacks.

The source said Western intelligence agencies believe Adnani is at the heart of ISIL international attack planning.

"As far as we're concerned, he is top of our target list," the source told CNN.