The 1990 Trust has accused The Sun newspaper of stirring up Islamophobia in the wake of the London terrorist bombings.
The charity, which campaigns against racism, has criticised the paper for running a front-page story that compared Muslim academic Professor Tariq Ramadan to the extremist cleric Sheik Omar Bakri Mohammed.
The trust said Ramadan is known for his progressive beliefs, and it is calling on The Sun to apologise. Ruhul Tarafder, a spokesman for the trust, said: "The Sun's sensationalist, disgraceful and irresponsible story is simply an attempt to fuel Islamophobia.
"Tariq Ramadan is a highly respected moderate Muslim scholar and was one of the first to condemn the London bombings. This demonisation does nothing but promote hostility towards Muslim communities."
The Sun did not return phone calls.
Separately, the Council of Ethnic Minority Voluntary Sector Organisations has set up a free helpline for Muslims who are verbally or physically attacked.