The European Union’s anti-terrorism chief will tell EU interior ministers on Thursday about the “major security threat” that the increase of foreign fighters in Syria poses.

A note for the meeting from the office of EU Counter-Terrorism Co-ordinator Gilles de Kerchove stresses that the number of fighters travelling back and forth from Syria is increasing. The note, obtained by The Associated Press, specifically calls for better use of airline passenger information available to security officials to keep track of when and how rebels move to Syria.  

Such legislation remains stuck in the European Parliament, and could remain there for months to come, considering the furor over the revelations from National Security Agency leaker Edward Snowden about wholesale data-mining of EU citizens.  

The note does not name the number of fighters traveling from the 28-member EU to Syria.  

'They are not some romantic freedom fighters.' - Britain’s counter-terrorism chief Helen Ball

But the 11 western European countries with the biggest contingents in Syria are estimated to have some 1,200-1,700 people among rebel forces, according to government and analyst figures compiled by the AP for a story published Tuesday. That compares to estimates of 600-800 from those countries in late spring.  

Belgian Interior Minister Joelle Milquet organized an international gathering on the subject with a dozen counterparts on the eve of the EU meeting.  

“We have to anticipate the returns (of fighters from Syria), the ways to handle this, the prevention measures and especially the exchange of information on the travels,” she said.  

'Hundreds' of fighters from Britain

Last month, the head of Britain’s domestic spying agency said the intelligence service had seen “low hundreds of people” from Britain go to Syria and that some have since returned — stoking fears extremists could pose a domestic threat.  

Some of them, said Britain’s counter-terrorism chief Helen Ball on Wednesday, “decided to get themselves trained to use weapons or build bombs and engage in fighting”  

“They are not some romantic freedom fighters,” Ball said.  

EU interior ministers will also be looking at ways to co-operate more closely with Syria’s neighbour Turkey, through which most of the fighters move to get to the Syrian rebel camps.

“The EU should offer to assist Turkey in improving controls at borders and airports and should do more to help in preventing radicalization of individuals, especially in refugee camps,” the note said.  

A senior EU official, who demanded anonymity because of a sensitivity of the issue, said that beyond the fighters from the 28-nation EU, there were also some 500 from Balkan nations, highlighting the contribution from small nations like Bosnia and Kosovo.

“Kosovo has 80 to 100 for two million people,” he said.  

The official said the total number of EU fighters could be well above 1,000, bringing it roughly in line with the AP assessment.  

The EU-based rebels are drawn by recruiters arranging travel and comfortable lodging. They instill militant Islam that EU security officials see as a potent threat once the fighters return home.

“There are cases where individuals continue travelling back and forth,” the note for the ministers said. Rebels are often seen as heroes to a small section of youths upon return, making them ideal to further foster recruitment.