An amendment has been tabled for the equal marriage bill for England and Wales, which would allow straight couples to enter into civil partnerships, amidst fears that such an amendment could wreck the bill.

The amendment, tabled by former Lord Chancellor, Lord Mackay of Clashfern, who is strongly opposed to equal marriage, and who spoke during the House of Lords debate on equal marriage last week against the legislation, would add provisions to allow straight couples to enter civil partnerships.

When asked by PinkNews.co.uk his reason for introducing the amendment, Lord Mackay simply said: “My amendment is intended to make clear what is the scope of same sex marriage.”

There have been widespread fears that adding an amendment to the Marriage (Same Sex Couples) Bill, to allow provisions for opposite-sex civil partnerships, could wreck the bill.

A clause was added during the House of Commons Third Reading on the bill, which has promised a review of civil partnerships in the future.

During the House of Commons debate, anti-equal marriage Conservative MP Tim Loughton, proposed a similar motion, but said that he did not propose it to derail the bill. He told MPs: “If the Government think it is right to extend marriage to everyone then it has to be right to extend civil partnerships to everyone too.”

In the end, just 70 MPs voted with Mr Loughton, significantly less than had been feared before Minster for Equalities Maria Miller, and the Labour Party were able to agree on the wording for a clause promising a civil partnerships review.

During the debate last week, Lord Mackay said that marriage should be primarily for “natural procreation” and went on to say that “it can never be the same for same sex couples,” and voted for an amendment which would have denied the bill its second reading.

The bill comes back in committee the week commencing 17 June. It will have its report stage on 8 July and third reading on 15 July.

Ministers are hoping that the bill will have Royal Assent before summer recess, at the end of July.

Former Archbishop of Canterbury, Lord Carey, has also tabled a bill which could wreck the equal marriage bill for England and Wales, by suggesting that there be two “tiers” of marriage.

Equal marriage critic Lord Dear has proposed another, similar amendment to the Marriage (Same Sex Couples Bill), protecting those who believe marriage is “the union of one man and one woman for life to the exclusion of all others.”

Out4Marriage has launched the LobbyALord website in order to make it easy for members of the public to lobby Peers on the issue.