Prince George's County police added a dozen detectives to the vice squad yesterday in response to what they said has been an influx of drug dealers from the District of Columbia.

Police blame the increase in drug traffic in the county on the success of D.C. police in recent weeks in their campaign to drive dealers out of the city. "We have to get word to the people in D.C. that if they're enforcing the drug laws there we don't want the dealers here," said county Police Chief John McHale.

Most of the drug traffic in Prince George's County has been concentrated in the neighborhoods inside the beltway, just over the D.C. line. During the last two days, for example, county police arrested 17 persons on heroin and marijuana possession and distribution charges on Southern Avenue, Eastern Avenue and on George Palmer Highway.

All of the persons were arrested outdoors, said Deputy Police Chief Joseph Vasco, adding that drug dealers and users have been loitering in groups in some neighborhoods while they wait to transact business, just as they have done in the District along 14th Street NW and more recently at Seventh and S streets NW.

As part of a highly publicized attempt to combat drug traffic, D.C. police have sold oregano to prospective buyers of marijuana on Chapin Street, sent troops of police along Seventh and T streets to disrupt heroin sales, and in one incident, wore a bull's-head costume prior to making arrests to confuse drug dealers.

Vasco said drug traffic has been on the increase in the county since the beginning of the year, but that in the last few weeks it has been more conspicuous. He and McHale said they are convinced the traffic is coming from the District, but neither could offer any statistics in support of their assertion.

D.C. police Lt. Ronald Harvey, commander of the narcotics squad in the 3rd District, where most of the main drug centers in the city are located, appeared unsympathetic to Prince George's problem.

"There's no way I can know who's leaving the District but all I know is they're not leaving fast enough," he said. "It's like ants. Maybe they're going over to your picnic table too, but I can't tell if they're at yours because there are so many here."

Prince George's County police contend that the increased heroin traffic in the county has led to an increase in other types of crime, particularly burglaries and armed robberies. During the first seven months of this year, for example, overall crime increased 7 percent over the previous year.

"We feel that drugs inspire other crimes, and that if we take drugs out of here maybe we'll have fewer crimes," McHale said.

The 12 detectives who joined the county vice squad were transferred from other assignments throughout the county, McHale said. In addition to making arrests on heroin and marijuana charges, the detectives will try to cut down sales of PCP by infiltrating the groups that manufacture it in laboratories in the county, McHale said.

"We're calling this 'Operation Wolf Pack' because the detectives will travel in small groups of wolf packs," McHale said. The detectives will work undercover.

Sales of PCP have been increasing in the county, McHale said. During the first seven months of the year, police closed down two PCP labs and seized $160,000 worth of the drug, which is popular among county teen-agers.

Since January, county police arrested 42 persons on PCP charges and arrested more than 500 others on other drug charges. The most recent PCP arrests occurred two weeks ago, when police charged 20 members of the Phantom motorcycle gang with PCP possession and distribution as a result of 10 separate raids around the county.