The Conservative MP for Hendon has said that allowing equal marriage was part of an “open-ended process”, and said that it could lead to polygamous marriages being made legal.

Matthew Offord MP, said that he had not made links between polygamous marriages and same-sex marriages, but went on to assert that allowing the defintion of marriage to be “flexible” would lead to pressure to legalise polygamy.

Whilst denying the suggestion that he compared polygamy to equal marriage, Mr Offord said: “The evidence from around the world is that once marriage is redefined, with a flexible definition, pressure always grows for redefinition.

“There are several advocates of same-sex marriage who openly support changing the law to permit polygamy.”

He raised several rulings across Canada and The Netherlands, which allowed three parents to be recognised on behalf of a child.

He went on to say: “Already polygamy exists in this country. The government recognised in 2007 that there are over a thousand bigamous or polygamous marriages in England and Wales.

“The unintentional consequences of this bill will allow the introduction of polygamous marriage… I am angry that I have defended people who are homosexual, many in this chamber, and then they deride me as a bigot by sending me text messages saying that because I don’t support them, I am wrong. I bitterly resent that.”

He also said that it was “not fair” for a cohabiting lesbian married couple to avoid inheritance tax on their property upon the death of one of the women, when two sisters living together would not be entitled to the same benefit.

He said: “Marriage as a union between one man and one woman has not changed over thousands of years. This legislation would create ungendered marriage, with two types of marriage available – same sex and opposite sex marriage.

“One reason I oppose the bill is that it will be an open-ended process. The consequences of which the govenrment does not seem to have considered. The bitter irony is that it would only lead to greater inequality.

“Civil partners already have the civil rights of partners, which is something already denied to many who already co-habit. Two sisters who live together for many years”

He said that it was unfair that same-sex couples would have two choices – marriage, or civil partnership – if the bill were to pass.

He criticised the government for changing its stance on the plan, and said he felt let down by past assurances that equal marriage would not go ahead upon legalising civil partnerships becoming law.

“Is that the same law that says marriage is between one man and one woman. If that is so another government can come along and change the definition to as many partners as they want.”

He then said he would be voting against the bill.

Dr Offord previously wrote to a PinkNews.co.uk reader in his constituency to say that he did “not see the point” in legalising equal marriage because gay couples could not have children.