President Francois Hollande said Monday France would conduct surveillance flights over Syria to help it prepare air strikes on Islamic State jihadists.

"I have asked the defence ministry that from tomorrow surveillance flights can be launched over Syria, allowing us to plan airstrikes against Daesh (the Islamic State group)," Hollande told a press conference in Paris.

"What we want is to know what is being prepared against us and what is being done against the Syrian population," he added.

Hollande confirmed France would not send ground troops into Syria, saying it would be "unrealistic."

"It's for regional forces to take their responsibilities. France, however, will work to find political solutions."

He said finding a political "transition" that sidelined Syrian President Bashar al-Assad was "essential".

- 'Late in the game' -

France currently only participates in missions against IS in Iraq, in the context of Baghdad's request for international help against the jihadists.

Analysts were lukewarm about Hollande's strategy shift.

"It's above all else a domestic political gesture, with in the background the message 'look, we're doing something'," retired French general Jean-Claude Allard, director of research at the Institute of International and Strategic Relations (IRIS), said.

Myriam Benraad, of the Centre of International Research (CERI) in Paris, said: "It's a direct response to this disaster, but it comes a little late, and airstrikes are not enough to solve this problem."

Hollande's initiative comes at a time of growing concern in the West over reports that Russia is toughening its military stance in Syria.

Moscow has been a bulwark of military and diplomatic support to the Assad regime, and is promoting an expanded coalition against IS that includes countries in the region as well as the regular Syrian army.

The United States government expressed concern on Saturday over reports of "an imminent enhanced Russian buildup" in Syria.

Secretary of State John Kerry "made clear that if such reports were accurate, these actions could further escalate the conflict, lead to greater loss of innocent life, increase refugee flows and risk confrontation with the anti-ISIL coalition operating in Syria," the State Department said.

Concerns of being sidelined by Russia have combined with the growing surge of interest in the fate of refugees from the war, pushing France to take a more active role in Syria.

France has played a low-key role in the recent diplomatic push to find a political solution to the country's civil war, which has included an unprecedented meeting in Doha on August 3 between the top US, Russian and Saudi diplomats.

Prime Minister David Cameron said Monday he wanted Britain to extend its anti-IS bombing campaign to Syria as well as Iraq but stressed he would return to parliament for formal authorisation to do so.

Cameron confirmed however that Britain had carried out a drone strike in Syria in August for the first time, killing three IS militants, including two Britons, in what he called "an act of self-defence".

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Cameron International