A politician for Germany’s far-right Alternative für Deutschland party, which campaigns on an anti-Muslim ticket, has converted to Islam and left the party, a spokesman has confirmed.

Arthur Wagner, a leading member of the party in the eastern German state of Brandenburg, said he would not comment on his reason for leaving the party, but confirmed to a Berlin daily that he had converted to Islam and that he had renounced his party membership on 11 January.

“It is a private matter,” he told Der Tagesspiegel, adding that it had been his decision to leave.

A party spokesman said it had not been concerned by Wagner’s conversion, and also confirmed it had not pushed him to leave. It claimed it had not known of his move when he announced his departure.

“The party has no problem with it,” said Daniel Friese, a spokesman for the Brandenburg branch of the AfD. Being a Muslim was no barrier to being a member of the party, he said, despite the fact that among the party’s campaign slogans before September’s general election were “Islam has no place in Germany” and “Against the Islamisation of Germany”.

The party has been accused of stoking resentment towards the hundreds of thousands of Muslim refugees living in Germany. “The AfD contains interest groups for Muslims, Christians and homosexuals,” Friese said.

Wagner, who formerly belonged to the Christian Democrats and joined the AfD in 2015, is an active member of the German-Russian community and the vice-chair of the regional Russian-German committee. He has also acted as a translator for refugees from Chechnya.

He is believed to be the first AfD member to have converted to Islam after joining the party, although the party spokesman said there were other Muslims within its ranks.

The AfD was voted into the Bundestag for the first time last September as the third largest party. If talks towards forming a grand coalition government between Angela Merkel’s conservative alliance and the Social Democrats are successful, the AfD would become the main opposition party in the Bundestag, with the right to speak second in debates, after a member of the government.

Wagner’s case, although considered highly unusual, was being compared by German media to that of Arnoud van Doorn, a member of the Freedom party of the Dutch far-right politician Geert Wilders, who was asked to leave the party in 2013 when it emerged he had converted to Islam and travelled to Saudi Arabia to perform the hajj.