London: Up to 11,000 fighters from more than 70 nations have joined the struggle in Syria against President Bashar Al Assad, almost doubling estimates made earlier this year.

The number of individuals from western Europe taking up arms has tripled to reach 1,900 and includes up to 366 from Britain, according to research by the International Centre for the Study of Radicalisation (ICSR) at King’s College, London.

The number reported from France has quadrupled while Belgium has the highest per capita rate. The report showed that Arabs and Europeans made up the bulk of foreign fighters, with up to 80 per cent, but militants from south-east Asia, North America, Africa, the Balkans and countries of the former Soviet Union were also represented.

Syria is becoming as big a magnet for Muslim fighters as Afghanistan was in the 1980s when an estimated 35,000 foreigners joined the mujahideen ranks against Soviet invaders.

Prof Peter Neumann, a director of the centre, said the dramatic increase from its estimate in April may be linked to the fact that some European governments had paid more attention to the issue. But the greater cause was more probably the deepening involvement in the war of Shiite fighters from Lebanon and Iraq on the side of Al Assad, whose Alawite faith is an offshoot of Shiite Islam and who is backed by Iran.

“For radical Sunnis, if you see this Syrian government supported by Shiite Iran and Hezbollah, it becomes almost a civilisational conflict, almost as if America has intervened in the Middle East,” said Prof Neumann.

Although only about 20 per cent of the sources stated which rebel groups the foreigners joined, the ICSR said that most of those who responded had fought for groups linked to Al Qaida. The ICSR said that from late 2011 to December 2013, between 3,300 and 11,000 individuals had gone to Syria to fight against the Al Assad government.