Armed police have raided several buildings in northern Germany city of Hil-des-heim, in an effort to crack down on Islamic extremists.

Local media report police searched a mosque and the apartments belonging to eight board members of a radical organization named "German-speaking Islam Circle Hildesheim".

Authorities suspect that the group has been radicalizing Muslims and encouraging them to join jihad.

Local media report the group ran lectures, seminars, sermons on "the hatred of infidels".

Local authorities say they have been watching the group for a long time.