PARIS (Reuters) - France said on Sunday the U.S.-led coalition fighting Islamic State should begin the battle on the group's Syrian bastion Raqqa while the offensive on Mosul is underway, Defence Minister Jean-Yves Le Drian said.

"I believe it will be necessary," he told Europe 1 radio.

Le Drian, whose country is the second-biggest contributor to the coalition, added that the battle on Mosul would be long and complicated given that Islamic State was embedding itself within the local population.

(Reporting by John Irish; editing by Gus Trompiz)