GABORONE, Botswana — The French Air Force says it flew at least two intelligence, surveillance and reconnaissance (ISR) missions last month over two Libyan towns that are strongholds of the Islamic State group (IS) to gather information on troop movements and map out possible targets for airstrikes.

A statement released by the French presidency said the surveillance flights were conducted over the IS group-held cities of Sirte and Tobruk.

The surveillance flights come against the backdrop of increasing calls for Western military strikes on IS in Libya, where the group has consolidated itself as it loses grip over the large swathes of territory it held in Iraqi and Syria.

This week, Israeli media reported that the IS group is now training pilots for a rudimentary air force believed to be made up of aircraft seized by militias from the fractured Libyan Air Force last year. Further, the group announced early this week that it has set up its own Islamic police force in Sirte and published images of hundreds of uniformed men holding brand new AK-47 rifles standing next to brand new Toyota HiLux pickup trucks branded with the group's flag.

According to the French statement, more surveillance flights are planned as Britain and Italy also consider military strikes on IS group targets to stop it from consolidating in Libya. Top French government officials have taken the lead advocating military strikes to contain the IS group in Libya, with French Prime Minister Manuel Valls warning that Libya risks becoming the next IS group haven if the West fails to take military action to stop it.

"We are living with the terrorist threat. We have a common enemy, Daesh, which we must defeat and destroy in Iraq and Syria, and probably tomorrow in Libya," he told Europe 1 radio on Dec. 11.

According to a report released by the United Nations Panel of Experts on Libya early this week, the IS group there has nearly 3,000 regular fighters who receive direct support and guidance from commanders in the group's de facto capitals of Raqqa in Syria and Mosul in Iraq.

French Defense Minister Jean-Yves Le Drian has also called on Western powers to support timely action to stop IS from taking advantage of political and security chaos to entrench itself in Libya: "Libya worries me because Daesh (IS) has installed itself by taking advantage of local rivalries. If we can unite the (opposing) Libyan forces against Daesh, it will no longer exist as they have sufficient military means to defeat the group," Le Drian said.

Commenting on the signing of a unity agreement between the two rival governments of Libya early this week, British Foreign Secretary Philip Hammond said his country stands ready to help stabilize Libya and fight the IS group.

"To ensure a lasting peace in Libya, all parties must maintain this momentum to create a government of national accord based in Tripoli," Hammond said. "The UK Government stands ready to work to help deliver a stable and prosperous future for all Libyan citizens, and to tackle the threat from Daesh and criminal gangs who have contributed to the migration crisis in the Mediterranean."

Hammond spoke amid reports suggesting that Britain is contemplating sending up to 1,000 troops in support of Italy which has proposed a task-force of 6,000 troops to train a unified Libyan Army and fight the IS group there. Daniel Kawczynski, a member of the British House of Commons' Foreign Affairs Select Committee said Britain should provide the Libyan unity government with military support, which may include airstrikes.

"We have to take them on, whether it's in Syria or whether it's in Libya. Now is the time to show extensive force against them, in coalition with other countries, to try to eliminate them," Kawczynski told British media. "If we don't take them on in Syria and we don't take them on in Libya then we are leaving ourselves to the possibility that they will just magnify in strength, their tentacles will spread even further."