German police on Thursday arrested a Syrian refugee suspected of links to the so-called Islamic State, a German prosecutor said, highlighting the potential security risks posed by Berlin’s open-door refugee policy, according to the Wall Street Journal.

The state prosecutor in the city of Dortmund, Sonja Frodermann, said a man who had registered as Leeth Abdalhmeed and was born in 1984 had been detained at the refugee shelter in Unna-Massen on Thursday afternoon on suspicion of having links to Daesh terror organization.

The arrest will heighten concerns among opponents of Chancellor Angela Merkel’s open-door refugee policy that Islamist terrorists might be hiding among the roughly one million refugees who entered Germany this year, half of them coming from war-torn Syria.

At least two members of the terrorist cell that killed 130 people in a series of attacks in Paris on Nov. 13 are known to have entered Europe via Greece as refugees using fake Syrian passports.

This week, Austrian police arrested two people at a Salzburg refugee shelter they suspect of being involved in the Paris attacks.

Sources: MENA