Tornado aircraft could be fitted with Paveway IV guided bombs or Brimstone missiles if David Cameron gives green light

RAF Tornado jets based in Cyprus are preparing to bomb Isis targets in Iraq and would be ready to strike soon after David Cameron gives the green light, defence sources have said.

Six Tornado GR4 aircraft, accompanied by a Voyager refuelling tanker have been flying reconnaissance missions over northern Iraq since they were deployed to the base at Akrotiri a month ago.

The aircraft could be fitted with Paveway IV guided bombs or Brimstone missiles suitable for carrying out strikes on small targets such as Isis vehicles.

An RAF Rivet Joint surveillance plane equipped with listening devices has also been flying missions from al-Udeid air base in Qatar to eavesdrop on Isis communications.

However, although the Tornados are ready to begin air strikes, sources said the task of choosing appropriate targets – many of them moving and small – would be a challenge for intelligence-gatherers. A campaign of air strikes may not be as easy or as persistent as the bombing of targets over Libya in 2011.

“My expectation is [British aircraft] will be actively involved, probably in a combat role within two weeks,” said Prof Michael Clarke, director general of the Royal United Services Institute thinktank.

The RAF has about 10 armed Reaper reconnaissance drones in Afghanistan, and these could be deployed in Iraq or Jordan if the war against Isis looks as if it may be prolonged. Sources indicated there were no plans yet to take the Reapers out of Afghanistan before British combat forces leave the country at the end of the year.

On Monday night the US for the first time launched ship-based Tomahawk cruise missiles against Isis targets in Syria. British Tomahawks, which are on submarines, are not yet within striking distance of targets in Iraq or Syria, official sources have suggested.

Scores of British special forces in northern Iraq, and possibly in Syria as well, are gathering what may turn out to be the most valuable intelligence on the ground. They are intercepting communications, looking out for Isis movements and identifying possible targets.

Defence chiefs will be asking for detailed legal advice about what to attack and how, and the general principles involved, including that of “collective self-defence”.

France said it would not stop its air strikes on Isis fighters or negotiate with the Algerian Islamists who in a video message published on Monday threatened to kill the French hostage Hervé Pierre Gourdel within 24 hours.

“That’s all the perfidy of terrorism, to resort to blackmail, death and threats,” the prime minister, Manuel Valls, told Europe 1 radio. “If we give an inch, we hand them a victory.”

President François Hollande has said French action would be confined to Iraq. French Rafale jets based at Dhafra, near Abu Dhabi in the United Arab Emirates, have attacked targets near Mosul. The French defence ministry said they destroyed a building containing vehicles, weapons and fuel. “The mission was carried out in direct coordination with the Iraqi authorities and our allies in the region,” it said.