Conservative MP David Burrowes has accused the government of creating an “adulterer’s charter” as part of its equal marriage reforms.

Mr Burrowes, who represents Enfield-Southgate in north London, says it’s because the same-sex marriage bill does not state what constitutes infidelity.

During this week’s House of Lords debate of the Marriage (Same Sex Couples) Bill, Conservative peer and equalities spokeswoman Baroness Stowell said it was “open to each couple” to decide whether or not it was necessary to be faithful to each other.

The Telegraph reports Mr Burrowes said: “This goes against everything the PM has said about his desire to try and strengthen marriage by extending marriage to same-sex couples.

“If the legislation is not urgently amended, it signals the abolition of the law of adultery. It will create an adulterer’s charter across both types of marriage, which far from strengthening this great institution will do irreparable damage to it.”

A government spokeswoman insisted that Baroness Stowell was not endorsing infidelity.

“She was simply making the point that it’s a matter for couples to decide on how they conduct their relationships,” the spokeswoman said. “She was not expressing a personal view.”

Responding to arguments from the former head of the High Court Family Division Baroness Butler-Sloss in favour of having a concept of adultery in same-sex marriage, Baroness Stowell said: “It is not the possibility of divorcing someone on the grounds of adultery that leads someone to be faithful to the person they are in a relationship with.

“What makes people faithful is far more complicated than that.”

She added: “In terms of the law, marriage does not require the fidelity of couples.

“It is open to each couple to decide for themselves on the importance of fidelity within their own relationship.”

Lord Carey, the former Archbishop of Canterbury, accused Baroness Stowell of downgrading marriage as a “committed union to the exclusion of all others”.

The staunch equal marriage opponent said he was “saddened” by her remarks.

Peers will resume debate of the bill in the House of Lords on Monday.

Earlier this year the House of Commons Public Bill Committee received testimony from both advocates and critics of the bill.

David Burrowes was a member of the committee and accused PinkNews of “fomenting hostility” and “abuse” against equal marriage opponents during an exchange with PinkNews and Out4Marriage founder Benjamin Cohen.