A Government bid to allow gay couples to adopt children faces defeat in the House of Lords tonight.

Tories and Labour rebels say they will block the proposal, claiming it would undermine marriage and childhood stability.

A clause in the Adoption and Children Bill would allow unmarried couples in stable relationships to adopt children jointly. Under present law, a gay individual can adopt but a gay couple cannot.

Opposition in the Lords will be led by Tory peer Baroness O'Cathain and is likely to include several Labour peers.

Supporters of a change in the law say there is a shortage of adoptive parents for older children. It is crucial, they argue, to do whatever is necessary to get more children out of care homes.