French forces on Sunday bombed the Islamic State (Isis) terrorists in Syria for the first time as they justified it as an act of "self-defence".

After running surveillance and reconnaissance mission for some three weeks, the French fighter jets raided dozens of Isis targets in Syria on Sunday morning, The Guardian reported.

France had joined the US-led coalition on condition that its forces will carry out its own surveillance and will bomb targets identified during the reconnaissance missions.

French President Francois Hollande told the press that the operation to "fight the terrorist threat" was coordinated with partners in the region.

Hollande made the announcement hours before joining world leaders for the start of the United Nations General Assembly in New York. "Our country thus confirms its resolute commitment to fight against the terrorist threat represented by Daesh (Islamic State). We will strike each time that our national security is at stake," the French presidency said in a statement.

French Prime Minister Manuel Valls told local television channels that the country has bombed the Isis in an act of self-defence, Reuters reported.

"We are hitting Daesh because this terrorist organization prepares its attacks against France from Syria. We are acting in self-defense," Valls said, using an Arabic name for Islamic State. Valls told BFM-TV that several Isis training camps were targeted in the raid.

France has witnessed several Isis-inspired terror attacks, including one on the Paris office of satirical weekly Charlie Hebdo in which 12 people died, this year.