Muslim leaders have demanded the same legal exemptions as the Church of England in legislation to introduce marriages for same-sex couples.
The Muslim Council of Britain (MCB), with more than 500 affiliated mosques, charities and schools, said it was "appalled" by "utterly discriminatory" legislation on marriage set out by the government.
The proposals would allow faith groups to conduct marriages for same-sex couples but would ban the CofE and the Church in Wales from doing so.
The MCB secretary-general, Farooq Murad, said his organisation had strongly opposed marriage equality alongside other religions and was seeking an urgent meeting with culture secretary, Maria Miller, to express the concerns of many Muslims over the proposals. "No one in their right mind should accept such a discriminatory law," he said. "It should be amended to give exactly the same exemption to all the religions."