Two thirds of the rebel fighters in Syria are citizens of European countries, says a report of the London-based International Centre for the Study of Radicalisation. 

According to the report, entitled "Greenbirds: Measuring importance and influence in Syrian Foreign Fighter Networks'", around 10% of the foreign fighters are from Eastern Europe, Bulgaria included. 

The largest share of foreign fighters comes from the UK - 17.9% of fighters in Syria were from the UK, based on their database of 190 fighters identified from their social media accounts.

There is also a considerable number of citizens of France – 11.6%, Germany – 11.1%, Sweden – 10%, 8.9% from Belgium and 6.3% from the Netherlands. The report claims that there is a total of 5.3% citizens of Australia, Canada and the US. 

The investigation said that they created a database of the social media profiles of 190 Western and European foreign fighters. More than two thirds of these fighters are affiliated with Jabhat al-Nusrah or the Islamic State of Iraq and the Levant, according to the report.