A Metro board committee approved actions yesterday that would add 20 officers for street duty to the Metro Transit Police in response to a stepped-up anticrime effort on buses and increases in incidents on the subway.

A total of 12 transit police were shifted from subway to bus work after the May 18 one-day wildcat strike by bus drivers who protested that they were not receiving adequate protection.

Because of this "unexpected drain on personnel," Transit Police Chief Angus macLean wrote in an internal memorandum, "the rail system requires augmentation of transit police."

MacLean asked for 30 new full-time officers. His request was trimmed to 20. The board committee made a further cut yesterday.

It recommended to the full board that 10 additional full-time police officers be hired and trained and that 10 more civilians be hired to replace transit police presently assigned to radio dispatch duties. The full board will vote in two weeks and approval is expected.

Civilian dispatchers have been used with success by most suburban police jurisdictions. "We know it works, board member Cleatus Barnett said. He represents Montgomery County.

Metro transit policemen must undergo about seven months of training in all three jurisdictions - Maryland, Virginia and the District of Columbia - to receive guidance on legal matters peculiar to each area, plus basic police training. Civilian dispatchers would not require the same amount of training time.

Dennie W. Stewart, assistant transit police chief, told the committee yesterday that there has been a steady increase in incidents on the subway in recent months - from four in January to 30 in April. That coincides with dramatically increased traffic on the system due to the opening of the Silver Spring extension, but also with the thinning of the police presence that was so obvious in the early days of Metro.

In a separate interview late yesterday, Stewart detailed the incidents through April. Most of them involved destruction of Metro property, disorderly conduct and petty larceny. Also included were two purse-snatchings and two reported pickpocket incidents. Metro subway ridership averaged more than 200,000 a day last week for the first time.

D.C. police also have placed 10 men long-term commitment to keep them thre. If those officers are removed, a further request for transit police would be made, said Nicholas Roll, Metro's assistant general manager for transit services. Suburban jurisdictions also contribute to police patrol of Metro stations and bus areas.

In the first 20 days of June, transit police made 54 arrests on the buses and handed out 519 warnings, Metro officials said yesterday.