(CNN) A German far-right politician, whose party claims "Islam does not belong to Germany," has converted to Islam and resigned his post.

Arthur Wagner, a leading member of Alternative for Germany (AfD) in the eastern state of Brandenburg, left his position on the party's state executive committee on January 11 citing "personal reasons," according to Andreas Kalbitz, AfD's chairman AfD in the state.

Kalbitz told CNN that he only learned about Wagner's conversion in a telephone conversation with him a few days later.

"I was very surprised," he said. "He has been very active in the Christian wing of the party."

Wagner was first elected as an AfD representative in 2015 and was a member of the state committee responsible for churches and religious communities.