BBC correspondent Alison Holt outlines the main guidelines

The Health Minister, Paul Boateng, said it was important disadvantaged children were not "left to languish in the care system".

"What's changed is a determination to make sure that race, age and whether or not you smoke is not used as an excuse to prevent adoption."

Such factors are widely accepted to be taken into account during assessment, when social services try to match children and adopters with similar backgrounds.

Paul Boateng: "Nothing is more important that a loving, caring environment"

But the new guidelines say these factors should not be allowed on their own to stop what may be the child's best chance of a happy and secure future.

The rules should make it easier for transracial adoptions to take place and for older couples to adopt a child.

Paul Boateng wants the guidance "rigorously" implemented

Mr Boateng, who is responsible for children's services, said it was time to end "misguided" practices and stop treating adoption as a last resort.

"The importance of family life to a child cannot be overstated," he said.

"For too long adoption has been regarded as the last and least acceptable option.

"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 interests.

"This shows a fundamental failure to understand the nature of adoption."

He told BBC News that while such factors have to be taken into account they "shouldn't be the determining factor".

He added: "We mustn't let dogma get in the way. We have to put children first."

Call for 'careful monitoring'

The guidance stresses: "It is unacceptable for a child to be denied loving adoptive parents solely on the grounds that the child and adopters do not share the same racial or cultural background."

But it also says families should help adopted children appreciate their backgrounds and teach them now to deal with racism.

Agencies must be sure adopters have a reasonable chance of continued good health and have a duty to consider the effect of smoking.

But it adds: "The use of criteria whose application is in reality to ban people who smoke from adopting is not appropriate."

Listen to a debate on the adoption issue from Radio Four's 'Today'

The guidance also calls for careful monitoring of children awaiting adoption to avoid their "drifting within the care system".

Nearly 2,300 children were adopted in England in 1996. Numbers have fallen from about 22,000 in the early 1970s.

Social service chiefs will now have to review their policies and practice, and ensure adoption services are reviewed every three years.

Guidelines broadly welcomed

Director of the British Agencies for Adoption and Fostering, Felicity Collier, welcomed much of the guidance but warned against taking the section about race and culture "out of context".

She welcomed the acknowledgement that placement in a family of similar ethnic origin and religion was often most likely to meet a child's needs.

She said: "Many adults who were transracially adopted as children speak of feeling isolated and confused about their racial identity. We must learn from their testimonies."

Lee Chambers, of the BAAF: "This is not a change of direction"

Lee Chambers, also from the BAAF, played down the significance of the report.

She said: "This is not a change of direction. We are still very wary of this being misinterpreted. We don't want this to raise expectations among prospective adopters."