Last week, Dimitri Bontinck from Antwerp was in Syria looking for his 16-year-old son, Jejoen, while another father from Vilvoorde was reported to have departed on the same mission. As Flanders Today went to press, neither had made contact with his son.

Though there have been several reports from around Flanders and Brussels, no-one knows for sure how many young men have gone to take part in the Syrian rebellion, often convinced by radical Islamist groups that it is their duty. There have been numerous press reports from Syria that the rebels don’t actually welcome foreign volunteers, who can be more of a hindrance than a help.

The mayors of Antwerp, Mechelen and Vilvoorde, where the growth of radical Islamist youths is particularly acute, held a summit to consider a response to the problem. Any action would only be taken prior to departure or following return: The foreign ministry has made it clear it is unable to intervene on the ground in Syria unless the volunteers request it.

Many parents lay the blame on groups like Sharia4Belgium; its leader Fouad Belkacem made headlines at the end of last year after being jailed for hate speech. According to Mimoun Aquichouch, chairman of the Masgir Annasr mosque in Vilvoorde, the 20 or so youths who have left the city to fight in Syria were known to be problem cases, and the community failed to act in time. “They were looking for some sense in their lives, some direction,” he said. “But they found it in Sharia4Belgium, not with us.”

Politicians have suggested a wide variety of measures that might be taken to prevent or respond to the growth of militant groups.

• Bart De Wever, mayor of Antwerp: Use the system of municipal administrative fines to discourage the growth of radical groups
• Hans Bonte, mayor of Vilvoorde: Confiscate the passports of members of radical groups • Joëlle Milquet, federal minister of the interior: Forbid Belgian citizens by law from going to Syria to fight
• Serge Muyters, Antwerp police chief: Pay special attention to young men who suddenly decide to grow a long beard
• Nordine Taouil, Antwerp imam: Lock up would-be recruits in detention centres