The Prime Minister is to defy opposition from dozens of Tory backbenchers to back religious groups hosting same-sex weddings.

He will stop short of forcing groups against the policy from having to hold gay weddings, but will argue that homosexual couples should have the same rights as heterosexual partners.

Mr Cameron has been repeatedly told by some Conservatives not to focus on legalizing gay marriage, warning the party will see its traditional support base collapse.

But the Tory leader will join Labour’s Ed Miliband and Lib Dem Nick Clegg in arguing that gay couples should be able to tie the knot in a religious setting if they want to.

Mr Cameron has vowed to legislate before 2015, and next week Culture Secretary Maria Miller will launch the government’s plans in response to this summer’s consultation on the idea.

It is expected to allow religious groups to ‘opt-in’ to hosting same sex weddings. Many churchgoers and religious groups are fiercely opposed to the policy.