Barriers that prevent white couples from adopting black children would be removed by David Cameron under reforms to stop ethnic minority children languishing in the care system.

Black and Asian children wait on average three times longer than white children for an adoptive family. Critics say too many adoption agencies are hung up on race, and waste time trying to find perfect matches for children of increasingly complex ethnicity.

The Conservatives have been examining the situation in the United States, where the law changed ten years ago to prevent adoption agencies from giving weight to race when finding adoptive families. Within two years of the change, one third of states said the wait for placements among ethnic minority children had dropped.

A more relaxed attitude towards inter-racial adoption, which is now almost unheard of in Britain, would give thousands of children a loving home that they are currently being denied, the Conservatives say.

The move comes as new figures show a decline in the number of children being adopted from the care system. This year only 2,600 children have been adopted, down from 3,600 in 2004. Experts say the Government needs to take urgent action.

Although popular in the 1970s, inter-racial adoption is now virtually taboo. The 2002 Adoption and Children Act places a duty on local authorities to give “significant consideration” to culture and identity when looking for suitable parents. Many experts believe, however, that that is being interpreted too literally. The Conservatives say they would rewrite part of the law.

Michael Gove, Shadow Education Secretary, who was adopted, will head a Tory policy review into adoption, starting with inter-racial matching.

“If we can get more ethnic minority families to come forward, which ensures black children can be matched with black parents, that is fantastic. Our concern is some of the agencies allow the best to be the enemy of the good when it comes to judgments over who is best placed to adopt children,” he told The Times.

“Being adopted myself, I firmly believe it is better to have children out of care and adopted. The longer they are in care, the more difficult it is for them, and to find adoptive families.” However, Sue Cotton, head of adoption services at the charity Action for Children, who has led efforts to find more ethnic minority families to adopt children, disagreed.

“Any change in the law would be quite difficult if it denied the importance of racial identity.” she said.

“You have to balance that against the overall needs of the child. Where a significant attachment has already been formed with a carer, for example, you would have to look at that. But we have to learn from adults who went through it, and they say even where the adoption was successful in all other ways, a significant part of their identity is missing.”

Research from Julia Feast, an expert in adoption, found 71 per cent of children in inter-racial adoptions said they always “felt different” from the rest of their family, compared with 48 per cent in same-race placements.

Times Recommends

• Tree stump 'shows image of Virgin Mary'
• BBC drops Strictly judge for younger model
• Trafalgar Square 'reduced to a spectacle'