A Scottish bishop has written to prime minister David Cameron to tell him that the Catholic Church will ‘never’ recognise marriage for gay couples.

The Bishop of Paisley, Philip Tartaglia, was responding to reports that campaigners and some Scottish MPs are pushing for the Scottish government to open debate on the issue.

The bishop told the Herald that his letter said the church would never recognise same-sex marriage, even the government eventually enacts legislation to allow it.

He quoted Mr Cameron’s remarks at a Pride reception in Downing Street in June.

Mr Cameron told guests at the event: “I am pleased to announce that we are taking a further step, and I think a good step and a right step – and I say this as someone who believes in marriage, who believes in civil partnership, who believes in commitment – and that is to say that if religious organisations, if churches, if mosques, if temples want to have civil partnerships celebrated at religious places of worship, that should be able to happen and we should make that happen.”

The bishop wrote in response: “Your statement is vague enough to have more than one outcome in practice. But you and your government need to be aware from the outset that the Catholic Church will not register civil partnerships nor celebrate same-sex unions: not now, not in the future, not ever, no matter what legislation or regulations your government enacts or endorses.”

Civil partnerships were legalised in the UK in 2005 but in recent months, campaigners have stepped up efforts to secure full marriage equality and a number of senior government figures, including Mr Cameron, have said they will look at the issue.

Gay marriage supporters say that civil partnerships, which offer all the rights and benefits of marriage, are not adequate because they are a separate institution.

Instead, they argue, civil marriage should be opened up to everyone, while straight and gay couples should also have the right to civil partnerships.

Faith leaders have claimed that if civil marriage for gay couples was allowed, clerics would face legal challenges for failing to minister ceremonies.

Activists in Scotland believe that the Scottish government does have the power to grant full marriage equality, but Westminster must make a minor technical change to tax and immigrant laws.

A Scottish Green Party poll of 1,000 Scottish adults in April found that 58 per cent agreed that gay couples should have the right to marry, while 19 per cent disagreed.