A leading Roman Catholic politician who resigned from the government last month will vote against a bill that grants lesbians equal access to fertility treatment, it has been reported.

Ruth Kelly, the former Transport Secretary, is a controversial figure for many in the gay community.

She has a poor voting record on gay rights, and her membership of religious group Opus Dei has been questioned.

A friend of the former Cabinet minister told The Daily Telegraph:

“It would be easy for Ruth to make herself scarce from Parliament on the night of the vote, but I think you will find that she will be there – and that she will vote against the Bill.

“As a Catholic, she has little choice – she has felt for a while that her conscience wouldn’t allow her to simply duck out of this.

“She feels very strongly about this legislation, and she needs to cast her vote against it.”

Ms Kelly is to stand down as an MP at the next election. She has reportedly been unhappy about aspects of the bill that have been criticised by Roman Catholic leaders.

In a controversial Easter message this year the leader of Scotland’s Roman Catholic church attacked new rights for lesbian and gay parents.

Cardinal Keith O’Brien’s claimed that the Human Fertilisation and Embryology Bill will create “Frankenstein-like” human-animal hybrid embryos, a charge rejected by the government and scientists.

The Cardinal accused Prime Minister Gordon Brown of: “promoting a bill which denies that a child has a biological father, allows tampering with birth certificates, removing biological parents, and inserting someone altogether different.”

He also accused the government of trying to challenge “standards by which we have lived throughout our lives and by which Christians have lived for the past 2,000 years” and of not responding to the church’s concerns.

The government won a vote on the Human Fertilisation and Embryology Bill in the Commons in May.

MPs were given a free vote on several clauses and three Roman Catholic cabinet ministers, Ms Kelly, Des Browne and Paul Murphy, voted against the government.

The Commons also approved the creation of so-called ‘saviour siblings’ and proposals that will allow lesbians and single heterosexual women equal access to IVF and fertility treatments.

Ms Kelly’s appointment to the post of Minister for Equality in 2006 outraged gay equality activists.

A member of Opus Dei, she had never voted in favour of gay rights.

She was heavily criticised for delaying the implementation of the Sexual Orientation Regulations.

Ms Kelly has refused to say whether or not she personally regarded homosexuality as sinful.

A major row broke out in Cabinet in 2007 over plans to give Roman Catholic adoption agencies an opt-out from the Sexual Orientation Regulations, which outlaw discrimination on the grounds of sexual orientation when accessing goods and services.

Ms Kelly and former Prime Minister Tony Blair were said to support a faith-based exemption, but MPs and Cabinet colleagues defeated the idea.

The revelation that she is to rebel and vote against the Human Fertilisation and Embryology Bill on Wednesday is a blow to Gordon Brown.

The Prime Minister has slashed the Tory lead in the opinion polls and united his party behind his leadership during the economic crisis.

Ms Kelly has been MP for Bolton West since 1997 and is close to David Miliband, the heir presumptive to the Labour leadership.

She said her decision to leave Parliament and spend more time with her four young children was taken just after her 40th birthday in May.

She denied it was anything to do with the Embryology Bill when news of her departure emerged during the Labour party conference last month.