Heterosexual couples will be able to enter into a civil partnership after Theresa May announced her intention to change the law.

The Prime Minister said opening up civil partnerships to opposite-sex couples in England and Wales was necessary because some people “want to formalise their relationship but don't necessarily want to get married”.

Human rights activists welcomed the news but some Christian campaigners said it risked further undermining marriage.

At the moment, same-sex couples can choose to marry or register for a civil partnership but opposite-sex couples only have the option of getting married.

Mrs May said the change would provide couples who do not want to get married with greater security because their relationship will be formally recognised in law.

She said: “This change in the law helps protect the interests of opposite-sex couples who want to commit, want to formalise their relationship but don't necessarily want to get married.

“As Home Secretary, I was proud to sponsor the legislation that created equal marriage.

“Now, by extending civil partnerships, we are making sure that all couples, be they same-sex or opposite-sex, are given the same choices in life.”