Mayor Marion Barry has approved his transition team's proposal to close the troubled Cedar Knoll juvenile detention center in Laurel and transfer most of the youths to city group homes and halfway houses.

The proposal, which Barry included as a cost-saving measure in his fiscal 1984 budget proposal to the D.C. City Council, was strongly opposed by Police Chief Maurice Turner and other high-ranking police officials. They warned that the plan, if approved by the council, might make it easier for juvenile offenders to escape and commit more crimes.

"Bringing these kids back into the District would increase crime because you can't watch them and they can sneak out on you," Inspector Max Krupo, president of the Metropolitan Police Officials Association, said yesterday.

There has been a high incidence of escapes and assaults on staff members at Cedar Knoll, a minimum-security facility with no fence that now holds 144 persons. More than half the offenders held at Cedar Knoll and Oak Hill, the other principal juvenile detention center operated by the D.C. Department of Human Services in Laurel, escaped during one three-month period in 1981.

Turner was out of the country yesterday, on a tour of Taiwan, and was unavailable for comment. Deputy Police Chief Fred Thomas, commander of the Youth Division, said yesterday that "there are a lot of variables in the plan that might not make it so bad," though he opposed it when he served on the mayor's transition team late last year.

Barry's 1984 budget proposal includes $3.4 million to cover the phasing out of Cedar Knoll and simultaneous development of "a series of alternative programs for detained and committed youth." The transition team recommended that Cedar Knoll be closed by October 1984 and that the juvenile offenders be provided with community-based services.

Cedar Knoll is supposed to provide a program of education, recreation, psychological and therapeutic evaluation and counseling for juvenile delinquents, but critics long have contended that the facility is poorly operated and has caused suffering and lost opportunities for youths kept there.

"Operation of Cedar Knoll has historically been problematic," the transition team's report said. "The institution lacks sufficient staff to provide basic supervision and treatment; the plant is in need of major repairs; and the quality of programs provided has long been a source of legal and community concern."

About a third of the residents at Cedar Knoll are detainees, awaiting adjudication by the juvenile court, and two thirds were found guilty of criminal offenses but are not considered hardened criminals who must be kept in Oak Hill, a maximum-security facility.

A high-ranking D.C. budget official said yesterday that most of the youths at Cedar Knoll could be transferred to community-based foster care programs or group homes and the rest would be shifted to Oak Hill.

"It's possible we could begin phasing it Cedar Knoll out in 1983," a high-ranking budget official said yesterday.

The transition team study concluded that the city could save millions of dollars annually by shifting youths held at Cedar Knoll to community-based programs. It costs about $30,000 a year to keep an individual at Cedar Knoll, according to the study.

The transition team explored the possibility of converting Cedar Knoll to a women's prison. The District now pays the federal prison system to hold women. But a preliminary study indicated that it would cost the city $550,000 more a year to house female prisoners at Cedar Knoll than to keep them in federal facilities.