Saying that law enforcement is involved in an arms race with criminals, Prince George's County Executive Parris Glendening announced yesterday as expected that county police and sheriff's deputies will replace their six-shot service revolvers with semiautomatic weapons.

Glendening, at an afternoon news conference at police headquarters in Forestville, also called for tougher controls on sales of semiautomatic and automatic handguns in Maryland and Virginia, but said he was not proposing any such legislation to the Maryland General Assembly.

"Our police officers are simply being outgunned," Glendening said. "There is an arms race between the police and criminals in our neighborhoods. It can only lead to more danger."

The county will buy 1,100 of the 9 mm handguns made by Beretta USA in Accokeek for the police department and 140 for the sheriff's office over three years, Glendening said. The new weapons, holsters and ammunition will cost $545,000, and Glendening said he had asked the state legislature for financing. If state funding is unavailable, he said, the money will be found in the county's budget.

With the switch, county police join Maryland State Police and D.C. police in changing from .38-caliber revolvers to a 9 mm semiautomatic weapon. The 9 mm weapons fire more rapidly than revolvers and allow officers to fire an additional 10 bullets before reloading.

Since last July 1, officials said yesterday, county police have seized 140 automatic and semiautomatic weapons, including dozens of 9 mm semiautomatic handguns and several Uzi submachine guns, some equipped with silencers.

"The real issue is the safety of our officers," said Police Chief Michael J. Flaherty. Holding up an Intratec 9 mm machine pistol, Flaherty said: "It's not used for hunting, and it's not used for sporting events. In my opinion, they should not be sold in the United States."

Sheriff James V. Aluisi differed some with Flaherty and Glendening on the need for more controls on sales.

Aluisi, who has appeared in national advertising campaigns for the National Rifle Association, which opposes gun control, said he believes that laws should prohibit the sales of larger weapons such as machine guns with silencers. But some semiautomatic handguns are used in sporting contests, the sheriff said, and some are used for hunting.

"I think a background check is sufficient" for buying handguns, Aluisi said.

Under Maryland law, a criminal record check -- a weeklong process -- is made by computer on persons seeking to buy hanguns, according to the state police. Federal laws strictly control who can purchase automatic weapons.