But Muhammed Usman failed to reach the French capital in time for the terrorist attack that killed 130 people because Greece had detained him, it said.
Usman was part of a terror cell controlled by an IS leader called Abu Ahmed that joined the stream of refugees going to Europe in order to launch attacks there, CNN reported.
Investigators in Europe identified Urdu-speaking Usman as a suspected LeT bomb-maker, according to CNN.
The report did not say if there was a direct connection between LeT and IS or if Usman had joined IS on his own. LeT has reportedly been caught in the cross-fire of IS and al-Qaida, with IS criticising LeT as one of the anti-India groups acting on orders of "apostate" Pakistani army.
LeT created the text-book model for multi-pronged urban terrorist attacks using a very small number of attackers when it carried out the 2008 Mumbai attacks. The IS attack followed a similar strategy using only nine operatives to take huge toll and plunge a metropolis into fear.
Two men from Usman's group, Ahmad al-Mohammad and Mohamad al-Mahmod, reached Paris and blew themselves up outside the National Stadium during the attacks that also targeted a theatre and a restaurant.
However, Greek authorities found that Usman, who had started out from the IS caliphate-controlled city of Raqqa in Syria, and another terror cell member, Algerian-born Adel Haddadihad, carried forged passports and detained them for a month before setting them free to join the refugee trail.
CNN reported that according to its sources, "Investigators believe that delay was significant; as a result, they would not have a chance to become part of the Paris attacks."
On their release, Usman and Haddadihad received money arranged by Ahmed and joining the refugee trail eventually reached Salzburg, Austria, where they applied for asylum on Nov 14, a day after the Paris attacks.
According to CNN, "European investigators concluded that Haddadi and Usman were part of the same terror cell as the Paris bombers and, having failed to participate in that bloody day, were planning another strike."
But before that they could carry out any other attacks, they were arrested at a refugee centre on Dec 10 and eventually extradited to France.
CNN reported that senior European counterterrorism sources said that Haddadi and Usman face terrorism charges.
An examination of Usman's phone by authorities showed that when not contacting terror leaders and affiliates, he was using his phone to visit about two dozen pornographic sites, including "sexxx lahur" and "Pakistani Lahore college girls ... ImakeSex", CNN said.
