A prominent British imam has been forced to retract his claims that Islam is compatible with Darwin's theory of evolution after receiving death threats from fundamentalists.

Dr Usama Hasan, a physics lecturer at Middlesex University and a fellow of the Royal Astronomical Society, was intending yesterday to return to Masjid al-Tawhid, a mosque in Leyton, East London, for the first time since he delivered a lecture there entitled "Islam and the theory of evolution".

But according to his sister, police advised him not to attend after becoming concerned for his safety. Instead his father, Suhaib, head of the mosque's committee of trustees, posted a notice on his behalf expressing regret over his comments. "I seek Allah's forgiveness for my mistakes and apologise for any offence caused," the statement read.

The campaign is part of a growing movement by a small but vocal group of largely Saudi-influenced orthodox Muslims who use evolution as a way of discrediting imams whom they deem to be overly progressive or "western orientated".

Masjid Tawhid is a prominent mosque which also runs one of the country's largest sharia courts, the Islamic Sharia Council. In January, Dr Hasan delivered a lecture there detailing why he felt the theory of evolution and Islam were compatible – a position that is not unusual among many Islamic scholars with scientific backgrounds. But the lecture was interrupted by men he described as "fanatics" who distributed leaflets claiming that "Darwin is blasphemy".

"One man came up to me during the lecture and said 'You are an apostate and should be killed'," Dr Hasan told The Independent. "I want to go back – I've been going to the mosque for 25 years. It is my favourite mosque in London, and I have been active in the community for a long time. I hope my positive contribution will outweigh their feelings towards me."

But the imam's apology seems to have done little to resolve the matter. Earlier this week, the group issued a statement saying that Dr Hasan had been dismissed from his position as vice-chairman and imam at the mosque, and describing his views as a "source of antagonism in the Muslim community". Neither he nor his father were present at the meeting that voted for his dismissal.

Evolution "is not a matter of iman [belief] or kufr [disbelief]," said Dr Hasan, "and people are free to accept or reject a particular scientific theory." He also attacked clerics who made pronouncements about science they didn't understand, declaring that "any such fatwas about science from people ignorant of the subject matter are null and void."

Like Christianity, Islamic opinion is divided over evolution. More than a millennium before Darwin, Muslim scientists had posited ideas about species survival and generational change that bore striking similarities to Darwin's eventual theory.