Isis and other jihadi groups 'have 31,000 foreigners' in their ranks

Number has more than doubled in the past 18 months, says US-based consultancy

Abdelhamid Abaaoud, who planned the Paris attacks, is Belgian

The number of foreigners fighting for Isis and other Islamist networks in Syria and Iraq has more than doubled in the past 18 months, according to a US-based intelligence consultancy, which says that 31,000 overseas volunteers are part of jihadi groups.

The Soufan Group says that despite an effort by individual countries to stem the flow of militants leaving their homes, Isis in particular has been buoyed by an ever-growing stream of willing recruits. The group reports that the nationals of 86 countries are now fighting for it.

But of most concern to security services in Western Europe – one of the largest recruiting ground for Isis – will be that of the 5,000 fighters who have made their way to Syria, between 20 and 30 per cent are believed since to have travelled home. Several of those involved in last month’s Paris attacks had fought for Isis in Syria.

“So far as can be ascertained from their own accounts, the great majority of recruits [to Isis] continue to go to Syria with the intention of acting there rather than training to become domestic terrorists,” the report says. “But the attacks in Paris on 13 November 2015 may reflect a growing trend of overseas terrorism being planned and organised [by Isis].”

The Soufan Group estimates that three-quarters of the Western Europeans fighting for the militants come from France, the UK, Germany and Belgium. Of the 760 Britons that are believed to have joined Isis, up to 350 have returned to the UK.

The report comes as Syria’s highly fractured domestic opposition to President Bashar al-Assad met in Riyadh yesterday before two days of talks aimed at cementing a common stand against the Assad government.

The unity talks, which have excluded the most extreme jihadi groups such as Isis and Jabhat al-Nusra, aim to produce a common negotiating position for any future peace talks. “This is the first meeting where we have all the opposition, the politicians and the armed groups,” said Hadi al-Bahra, a member of the Turkey-based Syria National Council.

However, while the West lauded the talks – a British official described them as “an important first step” – among those not invited are the Kurds, who control much of northern Syria and who have been crucial in recent advances against Isis. There is also mistrust between some of the Syrian groups that operate under the loose banner of the Free Syrian Army, and the Kurdish militia, the YPG.

“It is not all-encompassing. It is not the consolidated, overall opposition platform,” one Western diplomat said. “I do not expect Riyadh to be a constructive step… The whole thing has been very acrimonious, and it looks like a Saudi-Turkish wish list.”

Iran, which along with Russia is fighting to prop up the Assad regime, said that the Riyadh summit threatened international multilateral talks on Syria’s future taking place in Vienna in January.

Meanwhile, fighting in the country continued. A Russian submarine armed with long-range cruise missiles has moved to the eastern Mediterranean, where it is expected to be deployed against Isis and other Syrian opposition groups, according to reports yesterday. The US-led coalition, which is bombing targets in Syria and Iraq, said it had hit 31 Isis targets on Monday.