Conservative MP Colonel Bob Stewart has told David Cameron and the Chief Whip Sir George Young that he plans to vote against equal marriage when the motion comes before the Commons next year.
The former British Army officer, who in 2010 became the MP for Beckenham in south east London, says he remains opposed to same-sex marriage ceremonies, although he now accepts civil partnerships.
In an interview with his local paper, the MP said: “To me marriage is a sacrament and, by definition, religion and tradition, a union between a man and a woman.
“As such, I view marriage, whether organised simply by the state or a combination of church, temple, mosque and state, to be different to civil partnerships and special in a unique way.
“Personally I am not in the least homophobic and have great and true friends who are gay.”
Mr Stewart went on to say: “I accept civil partnerships now although I must admit that I was vehemently against them when I was a young man. Of course we lived in different times then and society has changed – me with it.”
Mr Stewart has also reinstated his support for the anti-gay Coalition for Marriage (C4M) petition, which has called on the prime minister to drop his backing for marriage equality.
“On a point of principle I have informed the government that, should there be a vote in the House of Commons asking MPs to vote in favour of so-called gay marriages I will not support the idea. I have also signed the Coalition for Marriage petition,” Mr Stewart said.
The government is due to outline its official response to this year’s equal marriage public consultation later this month.
In November, Tory MP and former general Sir Edward Garnier told a constituent that gay couples in civil partnerships should feel free to describe their relationships as a marriage, although it should not have to require a change in the law.