In an extraordinary personal and political transformation, a former senior member of Geert Wilders’s virulently anti-immigrant Freedom Party (PVV) has converted to Islam – saying it was the party’s anti-Muslim rhetoric which led him to look more deeply into his new religion.

Arnoud van Doorn (46), formerly vice-chair of the PVV group on The Hague city council, announced his conversion on Twitter, first with a tweet saying he was about to make “a new beginning” – and later with another in Arabic proclaiming the Shahadah, his public declaration of belief.

Before leaving the PVV last year to set up a new party, Independent The Hague, Mr van Doorn was regarded as a staunch supporter of Mr Wilders, who wants to end immigration from non-western countries and described Islam as “a retarded culture” and the Koran as “a fascist book”.

Mr van Doorn – who is married, with three foster children – first declined to comment on his conversion, claiming his faith was “a private matter”, but subsequently appeared on al-Jazeera television to say the decision had been “a difficult one” and “not taken lightly”.

He said: “I can understand that a lot of people are sceptical because it was unexpected for them. But in my own close circle people knew I’ve been actively researching the Koran and other writings for more than a year now.”

He confirmed that it was the PVV’s hard line on Islam which, ironically, led to that life-changing interest.

“There were so many negative stories all the time about Islam that I felt I had to investigate for myself to establish what was true and what was not.

“I am not the sort of person who blindly follows the opinions of others without doing his own research.”

He confirmed he had been “guided” by the as-Soennah mosque in The Hague, which has been known for “fundamentalist” views.

“According to some people, I am a traitor, but people who know me support my choice”, said Mr van Doorn. “I have made mistakes in my life, but in converting to Islam I feel I have finally found my path.”