Two names on doomed Air France Flight 447's passenger list also appear on a list of radical Muslims considered a threat to France, according to French investigators.
French secret servicemen established the connection while working through the list of those who boarded the doomed Airbus in Rio de Janeiro, Brazil, on May 31.
Agents are now trying to establish dates of birth for the two dead passengers, and family connections.
There is a possibility that the name similarities are simply a "macabre coincidence," the source added, but the revelation is still being "taken very seriously."
Flight AF447 crashed in mid-Atlantic en route to Paris during a violent storm.
While it is certain that there were computer malfunctions, terrorism has not been ruled out.
Soon after news of the fatal crash broke, agents working for the DGSE (Direction Générale de la Sécurité Extérieure), were dispatched to Brazil.
It was there that they established that two names on the passenger list are also on highly classified documents listing the names of radical Muslims considered a threat to the French Republic.
A source working for the French security services told Paris weekly L’Express that the link was "highly significant."
France has received numerous threats from Islamic terrorist groups in recent months, especially since French troops were sent to fight in Afghanistan.
Security chiefs have been particularly worried about airborne homicide attacks similar to Sept. 11.