A leading member of the Conservative party has launched a full-frontal attack on the rights of lesbian and gay couples to equal parenting rights.

The Human Fertilisation and Embryology Bill is due before the House of Lords today.

It contains new rules that will allow the gay and lesbian couples to become the legal parents of a child conceived through donated sperm, eggs or embryos.

Iain Duncan Smith, a former leader of the Tory party, said that the proposals remove the need for a father and therefore threaten society.

“Another nail will have been hammered into the coffin of the traditional family and another blow will have been struck against fatherhood,” he wrote in the Mail on Sunday.

“This move could not have come at a worse time.

“Just as we are beginning to appreciate the vital role fathers play in the successful upbringing of children, Labour ministers are sending out the utterly wrong signal that fathers don’t matter.”

Gay equality organisation Stonewall said the proposed new rules would merely give legal status to gay couples that already exists for heterosexuals.

“At a time when three million children in this country are growing up in single-parent households, it seems odd there should be this obsession with a few hundred who have an opportunity to have a second loving parent,” said chief executive Ben Summerskill.

Mr Duncan Smith’s comments are at odds with the gay-friendly image the party is keen to cultivate since David Cameron took over as leader.

“To equate lesbian households with so-called ‘broken homes’, as Iain Duncan Smith has done, is as ludicrous as his attack on all unmarried couples and the Conservatives’ bizarre wish to impose fathers on lesbian households suggests that some Tories simply don’t understand anything beyond their own traditional backgrounds,” said Lib Dem MP Evan Harris.

Mr Duncan Smith’s concerns about the new Human Fertilisation and Embryology Bill are likely to be echoed by many members of the House of Lords when the legislation is discussed today.

The Archbishop of York is expected to oppose the bill and many Tory peers will speak out against equality for gay and lesbian couples.

Opposition is not restricted to the Tory party – 45 Labour MPs have signed a motion saying the bill is “profoundly misinformed and clearly undermine the best interests of the child.”

The leader of Britain’s Catholic Church, Cardinal Murphy-O’Connor, has criticised the planned Human Fertilisation and Embryology Bill as “profoundly wrong.”