Businessmen who allow school-age youngsters to loiter on their premises during school hours would face fines, and the youngsters' parents could face fines or jail, under a new crime-fighting proposal announced yesterday by the executive committee of the D.C. Commission on Crime and Justice.

"This legislation would fine businesses, such as lunch counters, games arcade owners and pool rooms" if they allow truant youngsters to remain on premises, the commission said.

"The parents could also be fined or jailed for a second violation, after an initial warning."

The proposal was one of 48 preliminary recommendations from the 35-member executive committee of the anticrime commission appointed by Mayor Marion Barry Jan. 27. The recommendations will be acted on by the full 100-member committee on Oct. 1.

Many of the plans, including the new truancy proposal, would require action by the mayor or City Council in order to take effect.

The committee yesterday suggested expanding drug detoxification faciliities and "Neighborhood Crime Watch" programs; starting mandatory drug education programs in public schools, and setting up a new vocational training program for ex-offenders.

Other proposals include setting up a "crime prevention store" in which D.C. police would work with businesses to promote the use of crime-prevention devices.

Commission vice chairman Lawrence P. Doss said the executive committee released its report now because the commission had said it would complete its work in six months and had been receiving numerous inquiries about its recommendations.

"There was some discussion about whether putting something out at this time would look like it had something to do with the political race. It did not," Doss said in answer to a question about the timing.

Doss said the commission is studying the cost of each new proposal, adding: "We are going to have to look at where the dollars are, and we may have to change the priorities."

He said many proposals suggest expanding existing programs, such as Crime Watch, which are regarded as successful.

Doss said only one-third of District neighborhoods participate in that program, which focuses on neighbors watching out for each other's property.

In describing the proposed "curfew violation act," Doss said the law is aimed at keeping youngsters in school. "If the kid drops out, he won't get a good job, and unemployment is connected with crime. Dropouts get into drug activities and others that lead to crime."

Doss said the District of Columbia already has a similar law dating from the 1920s and carrying fines of $10 or less.

The new law, modeled after those in Baltimore, Philadelphia and other cities, would increase penalties and tighten enforcement of the truancy law, he said.

Barry said yesterday that the recommendations "are not abstract pie-in-the-sky proposals" and pledged his support for those adopted by the full commission, which includes representatives of the city's legal, business, labor, religious, academic and civic groups.