BREMEN, Germany (Reuters) - The northern German city-state of Bremen shut down an Islamic cultural center on Tuesday after police raided it and the apartments of 12 of its members on suspicion of associations with Islamist militants.

Bremen Interior Minister Ulrich Maeurer said The Islamic Association Bremen was closely linked to a similar cultural organization that was banned after some of its members joined the Islamic State (IS) insurgent group in Syria.

More than 220 officers participated in the raids, confiscating mobile phones, computers, hard drives and other memory cards, Maeurer told a news conference.

No arrests were made. Police also searched a car repair shop in Delmenhorst, just outside Bremen.

“This organization has promoted the radicalization of people, and support and following for IS. It really does mean that people who live in our immediate neighborhood are willing to become terrorists overnight,” Maeurer said.

“So I must sound cynical when I ask: What security do we have when they only plan attacks in Syria? We must assume that this could also happen in Germany.”

Bremen authorities banned the Culture and Family Society in the city in December 2014, saying that it had promoted jihad (holy war) and martyrdom among members, six of whom died while fighting with IS in Syria.

The German federal police chief said last month that the number of Islamist militants returning to Germany from Syria and Iraq was on the rise and more than 400 people were under surveillance.