Denmark's security service said on Sunday it suspects around 80 people have travelled from Denmark to Syria to join the civil war since mid-2012.
In a report, the service known as PET said those who travel to Syria are mainly Sunni Muslim men aged between 16 and 25. At least seven were killed in Syria and around 40 have returned to Denmark again, PET said.
The Syria conflict has attracted hundreds of foreign fighters from European countries, many of whom have joined rebel groups.
The Norwegian intelligence service PST has said an estimated 30 to 40 people and possibly more - have left from Norway, including two teenage sisters aged 16 and 19 who made headlines last month.
The Danish recruits are mainly from "Islamist environments," and criminal gangs, PET said. It also warned that the number of those with ties to criminal gangs that join Islamist circles is increasing.
It said there is active recruitment in Denmark of young, socially vulnerable people and that the recruiters approach their targets directly and through social media.
"The threat and the security risks tied to the increasing number of people from Denmark that participate in the armed conflict in Syria is PET's highest priority right now," PET chief Jakob Scharf said.
"It is our assessment that among those who have traveled there are a number of people who have joined groups in Syria that share al-Qaeda's global, militant Islamist ideology," the head of PET's center for terror analysis, Soeren Jensen added. [AP]