The Fatih Mosque in Germany’s Bremen received a letter containing unknown powder Saturday.

The letter caused a major security measure by the police and firefighters to determine if the powder was dangerous. Upon the conclusion of the tests, it turned out to be harmless.

Aside from the powder, the envelope contained a letter which was described by the police as "right extremist." The letter was sent through postage, and an investigation has been launched, the police said.

The vice president of the Islamic Federation Bremen, Vahit Bilmez, said the parents of the 250 children attending their weekly Quran course were deeply concerned. "We strongly condemn and detest this deed against our community and thank the swift action of the security authorities," Bilmez said.

The Fatih Mosque – belonging to the Islamic Community National View (IGMG), one of Germany's largest Muslim-Turkish associations – received last week an anonymous bomb threat among other mosques in Germany. As a result of the threat and the right extremist terror attack in Hanau the mosque is under the protection of the police. At least once an hour and at irregular intervals the police check on the third-largest mosque of Germany, a spokesman said.

This wasn’t the first time a letter containing a suspicious powder has been sent in Bremen. In the last few weeks, different offices of political parties and members of the parliament received similar letters, the police said. For the first time, a mosque was the target.