France has deployed special forces in northern Syria to advise the US-backed Syrian Democratic Forces (SDF) who are fighting the Takfiri ISIL group, a defense ministry official said Thursday.

France has deployed special forces in northern Syria to advise the US-backed Syrian Democratic Forces (SDF) who are fighting the Takfiri ISIL group, a defense ministry official said Thursday.

"The offensive at Manbij is clearly being backed by a certain number of states including France. It's the usual support -- it's advisory," the official told AFP, without giving further details on the deployment.

France until now has only acknowledged the presence in the region of around 150 members of its special forces, deployed in Iraqi Kurdistan.

The SDF, a US-backed Kurdish and Arab alliance, are on the northern edge of Manbij, a strategic town held by ISIL that serves as a waypoint between the Turkish border and the Takfiris' stronghold of Raqa.

The French special forces will not intervene militarily themselves and are not supposed to engage in combat with ISIL terrorists, the defense ministry official said.

Tabqa, another ISIL-held transit town which lies near Syria's largest dam, is also under attack.

France has 2,500 men in its special forces, of whom around 400 are currently deployed in 17 countries, mainly in the Sahel, the military said.

French Defense Minister Jean-Yves Le Drian had indicated last Friday, in remarks to a small state TV channel covering French politics, that French troops were helping operations at Manbij.

"We are providing support through weapons supplies, air presence and advice," he told the Public Senate channel.

In Iraqi Kurdistan, French special forces are already deployed, accompanying Kurdish peshmerga forces to the front line near the city of Mosul.

The French help the peshmerga to locate and neutralize improvised explosive devices (IED) and to handle 20-millimetre guns supplied by France.