The initiative is contained in guidelines to tackle the decline in couples taking in children without parents.

It coincides with the start of National Adoption Week, which the organiser, British Agencies for Adoption and Fostering (BAAF), hopes will help find homes for up to 10,000 children.

BAAF says it will specifically highlight the needs of brothers and sisters who want to stay together and children over five years' old.

Parliamentary Under Secretary of State for Health, Paul Boateng, said the government had intervened in the issue to bring it "back into the mainstream" of children's services.

'Fundamental failure'

The guidelines, outlined in a letter to social services and council chiefs nationwide, press for a relaxation of existing rules to allow adoption by parents over 40 or of a different race to the child.

Mr Boateng said: "Some local authorities still refuse to place children for adoption because one of the prospective parents is 40-plus, or is deemed the wrong colour, or smokes, or because of the belief that the family must be kept together, no matter what, even at the expense of the child's best interest.

"This shows a fundamental failure to understand the nature of adoption and its advantages for a child unable to live with his or her own family."

Paul Boateng: "Same race adoption not always in the child's best interest"

The number of adoptions has declined drastically in recent years, from 21,000 in 1975 to 5,797 in 1995, partly because of the tough vetting procedure which finds only 10% of applicants acceptable to adopt a child.

Race has become a particularly controversial issue, with the majority of social services holding children back until parents from the same ethnic origins are available, in order to prevent children becoming "racially confused".

The practice has come under frequent criticism, most recently in the case of Mike and Julie DeSouza. Mr DeSouza, the son of a Chinese father and a Caribbean mother, was rejected as an adoptive parent in early 1998 for "not having developed a good sense of black consciousness".

But Mr Boateng has been accused of promoting double standards, because his own department was originally responsible for introducing the policy of same-race adoptions.

Figures released for National Adoption Week by the BAAF outline the scale of the problem: