The United States and Soviet Union are expected to sign an agreement this year to cooperate in the war against drugs, a senior administration official says.

"The Soviets have started to recognize the problem, and the war in Afghanistan has something to do with it," said David L. Westrate, head of operations for the Drug Enforcement Administration, the lead U.S. organization in combating drugs.John C. Lawn, administrator of the DEA, and Ann B. Wrobleski, an assistant secretary of state for international narcotics matters, discussed possible areas of cooperation with Soviet officials during an April 27-30 trip to Moscow, Westrate said in an interview Wednesday.

Discussions are continuing, and the two sides are expected to sign a formal agreement in several months, although the exact date and place have not been decided, he said.

The development is significant because for years the Soviets denied they had a drug problem. The greater openness under Kremlin leader Mikhail S. Gorbachev and the exposure of Red Army troops to hashish and opium in Afghanistan have changed that.

The benefits of the agreement to the United States are not clear, said Westrate, but "the fact that they want to be in the international community in this field is important."

"You have to be able to pursue these cases beyond your own borders," he said. "There is also symbolic value for other countries, that they should be assisting as well."

Lawn and Wrobleski met in Moscow with officials from the Interior Ministry, which supervises national law enforcement; the Foreign Ministry; the customs service; and the procurator's office, which prosecutes cases.

Westrate said the proposed agreement will cover at least four points:

-Exchanging information on drug trafficking and drug routes.

-Exchanging drug samples: Analysts can determine the region or nation in which a drug originated using a chemical signature unique to the substance.

-Training: Soviet officials expressed interest in learning some of the techniques DEA agents use in fighting the drug trade.

-Exchanging data on "precursor chemicals," such as ether, used to process cocaine, and acetic anhydride, used to process heroin.

The Soviets told U.S. officials that their main drug problems were hashish and opiates, apparently smuggled in from Afghanistan, along with diverted pharmaceuticals and substances made in clandestine laboratories, said Westrate.

Drug dependence has grown at a rate of 50 percent a year in the Soviet Union, the officials told Lawn and Wrobleski, with an estimated 150,000 to 200,000 heavy users. Of those, 60 percent were estimated to be under 30 years old.

Of those whose who were dependent on drugs, 45 percent used cannabis, mostly hashish, 35 percent used opiates such as heroin, and 20 percent used pharmaceuticals, DEA officials said.