Harrow Council has been called upon to reject a popular definition of Islamophobia because it is a “back door blasphemy law”.

The authority is due to debate supporting the all-party parliamentary group (APPG) definition at a council meeting tomorrow.

National Secular Society CEO Stephen Evans has written to councillors, asking them to reject the motion.

He warns that it is at odds with the concept of free speech, and that it “conflates hatred of, and discriminaton against, Muslims with criticism of Islam”.

He explained that the society “unreservedly and emphatically condemns acts of violence against Muslims” and it appreciates the need to tackle anti-Muslim hatred.

But it has concerns around the APPG’s claim that Islamophobia is a “type of racism that targets expressions of Muslimness or perceived Muslimness”.

Mr Evans says this could mean Islamic practices, something he believes should be open to scrutiny and debate.

“We are concerned that allegations of Islamophobia will be, indeed already are being, used to effectively shield Islam and even extremists from criticism, and that formalising this definition will result in it being employed effectively as something of a backdoor blasphemy law,” he said.

“While the APPG authors have assured that it does not wish to infringe free speech, the content of the report, the definition itself, and early signs of how it would be used, suggest that it certainly would.

“I urge you to ensure that civil liberties are not be treated as an afterthought in the effort to tackle anti-Muslim hatred.”

Neighbouring Brent Council unanimously voted to adopt the APPG definition earlier this month.

Cllr Ahmad Shahzad, who brought the motion, said it showed that “Brent is a truly diverse, multi-religious and multi-cultural society – a borough that cares about and respects all of its residents”.

But the Government is yet to formally adopt the definition. In May, communities secretary James Brokenshire said the issue needs “more consideration”.

He said: “I am deeply concerned at hatred which is directed against British Muslims and others because of their faith or heritage. This is utterly unacceptable and does not reflect the values of our country.

“To get a firmer grip on the nature of this bigotry and division we agree there needs to be a formal definition of Islamophobia to help strengthen our efforts.

“That’s why I’m announcing the appointment of two experts to work closely with a cross-government working group, to thoroughly examine the options available to us that ensures wide-ranging acceptance and will have the positive effect intended.”