Liberal Democrat peer Baroness Williams says civil registrars should be allowed to refuse to provide marriages for same-sex couples in the same as those who opposed totalitarian regimes.

“It’s genuinely a conflict between equality and liberty,” Baroness William said on Monday evening in the report stage debate of the Marriage (Same Sex Couples) Bill.

Baroness Williams was speaking in favour of an amendment to allow civil registrars to opt out of providing same-sex marriages, which is currently being debated by peers.

The head of the National Panel for Registration (NPR), which represents marriage registrars in England and Wales, has recently warned the government against allowing civil registrars to opt of marrying same-sex couples.

In a letter to the Culture Secretary and Minister for Equalities, Jacquie Bugeja, chair of the NPR, said following discussions with its representatives there was no desire for a “conscience clause” to be inserted into the same-sex marriage bill.

The Equalities and Human Rights Commission (EHRC) in February declared that registrars should not be able to opt out of performing marriages for same-sex couples because unlike religious ministers they are deemed to be public officials.

Last month Baroness Williams supported an unsuccessful ‘wrecking’ amendment by equal marriage opponent Lord Hylton.

He suggested that the word “union” is strong enough to describe the bond between same-sex couples.

Baroness Williams argued that, as well as biological differences, men and women approach relationships differently – making opposite-sex couples the most “stable” parents.

She said: “Equality is not the same as sameness”.