Prince George's County Police Chief John W. Rhoads, who said he was reacting in part to the fatal shootings of two unarmed suspects by country policemen within the last month, said yesterday he will institute stricter guidelines on the use of firearms by police officers this week.

Chief Rhoads said the new guidelines will allow the use of "deadly force" - a category that includes firearms - only when there is "a clear and present danger" of serious injury or death to the policeman or someone else. Warning shots will also be prohibited under the new guidelines, he said.

"This more restrictive general order is being imposed because it is imperative that no one be needlessly slain or injured by a Prince George's County police officer," Rhoads said in a memorandum to his officers yesterday. "All officers may be assured, however, that the order will be drafted in such a way that their lives and the lives of others will not be exposed to further jeopardy."

Rhoads, in an interview at police headquarters in Forestville, said the new guidelines have been on the drawing board since last October, months before either of the two shooting incidents occurred.

He conceded, however, that concerns over those shootings within the county's black community and within the administrative of County Executive Winfield Kelly "accelerated the process."

Kelly and several of his aides met with Rhoads for three hours Saturday to discuss the police department's firearms policy. "They made it clear to me that immediate action was necessary to demonstrate the policy of the county government," said Rhoads.

The Saturday meeting followed by hours the early-morning police shooting of Abraham Dickens IV, 18, by Officer Lester J. Bethel in Landover.

According to police reports, Dickens was shot and killed as he was climbing out the rear window of a restaurant he had allegedly just burglarized. The reports said Officer Bethel ordered Dickens to "freeze." When he saw the suspect move his right shoulder, however, Bethel fired two shot-gun blasts, according to police accounts. Dickens was pronounced dead on the scene.

The other incident occurred on the afternoon of Dec. 24, when William Ray, 32, was shot and killed by Officer Peter F. Morgan as Ray was attempting to escape from the police station in Seat Pleasant. Ray, who had been picked up on charges of shoplifting two hams from a supermarket, was unarmed when he was killed.

In each instance, the victim was black and the policeman was white. Since Ray's shooting, several leaders of the county's black community have challenged the police department's use of firearms and handling of black suspects.

Office Morgan faces disciplinary charges within the police department for the Ray shooting. His actions are also being investigated by the county grand jury. In the meantime, Bethel has been placed on administrative leave until the police department's internal affairs unit completes its investigation of the Dickens shooting.

Rhoads said the revised firearms guidelines will not affect either case. He said yesterday that it appeared that Morgan has not followed the old, less restrictive guidelines in the Ray shooting. He said, however, that he would not comment on Dickens shooting until the internal police investigation is completed.

According to Rhoads, Prince George's was the only jurisdiction in the Washington region that allowed its policemen to fire warning shots. "We've been concerned about that for several months, and were planning to change it," said Rhoads. "When you've got a projectile that goes up, it must come down. That can be dangerous."

The chief said he and his district commanders studied the deadly force guidelines of several other police departments - including those in Washington and Los Angeles - while working on a revision of the Prince George's firearms policy.

"We found some that were more restrictive and some that appeared looser," said Rhoads. "But we found there were areas in which we had to make ours more restrictive. Clear and present danger is the theme of our new general order."

Rhoads said the five-page section on the use of deadly force was "far and away the most important section" of the thick department manual on police conduct. "We want our officers to keep that in their minds at all times," he added. "That's what it's all about."

Although the specifics of the new guidelines will not be presented to the police force until next weekend, Rhoads noted several portions of the firearms policy that will be changed.

Under the current regulations, a policeman may use firearms to effect the arrest of a suspect for a violent crime. The new guidelines, Rhoads said, would prohibit the use of deadly force in such cases unless the violent crime suspect poses a "clear and present danger" at the time he is being chased or apprehended.

In response to criticisms of his department by the black community, Rhoads noted that there has been a "dramatic decrease" in the number of brutality complaints since he took office. There were 19 such complaints last years, compared with 83 in 1975.

"Considering the fact that complaint forms are now in virtually every public building in the county and are far more accessible than they used to be," Rhoads said, "the decrease is significant."

Rhoads also said that the percentage of black police officers on the force has risen from 3.4 percent to 8.7 per cent in the last two years. "That's not as high as I'd like it to be. I want it to be the same mix as the community as a whole (Prince George's is about 25 per cent black), but we're getting there,"he said.