The Soviet Union charged yesterday that the United States uses its embassy in Moscow for espionage activities and that the Russians will make public "documentary evidence" if the Carter administration continues to "artifically aggravate" bilateral relations.
A strongly worded Soviet note was made public by Tass, the official Soviet news agency. Tass said the note was delivered to the State Department yesterday but American officials said last night no such presentation had been made.
The Soviet protest was a response to recent allegations of electronic bugging at the U.S. Embassy in Moscow, American officials said last week a secret shaft containing sophisticated listening and transmitting devices was discovered in the embassy's south wing. The shaft was reportedly connected to a previously unknown underground tunnel leading to a neighboring Russian apartment building.
An earlier private Soviet diplomatic communication accusing U.S. Embassy staff of unlawful penetration of the neighboring building was described by U.S. officials as "preposterous."
But yesterday's note, which was made public by Tass before being delivered to the State Department, was viewed as a tougher Soviet move. U.S. officials refused to comment on the Tass statement.
According to Tass, the Soviet note said that "an anti-Soviet campaign is being intensified lately in the United States with the aim of covering up the unlawful action of the U.S. Embassy in Moscow."
This campaign, the note said, attempts to divert attention from "the intelligence and subversive activities carried out by American special services from the embassy building."
The Soviet government, it said, "Has convincing evidence" that the embassy is used for "radio-electronic intelligence work to intercept communication lines, including radio-telephone conversations" in the Svoiet capital.
"Competent Soviet organs have in their hands real intelligence assignments and operator's logs for these posts as well as samples of electronic intelligence apparatus that were installed by U.S. Embassy staff members in one of the districts."
Making reference to "other forms of intelligence activities by American special services," Tass said the Soviet government warned the United States: "Should the American side advance further along the road of artificially aggravating this entire ussue that obviously damages our relations, the Soviet side will be compelled to make public the documentary evidence" about U.S. intelligence activities.
Although U.S. officials have consistently refused to comment on U.S. intelligence gathering activities in Moscow, it is commonly accepted among Soviet affairs specialists that radio-electronic and communication intelligence facilities do exist in the embassy building and that they are used to intercept Soviet communications.
The Soviet warning comes at a time when Soviet-American relations are undergoing a basic review in Washington. It follows a major speech on these relations by President Carter at Annapolis Wednesday. A preliminary Tass reaction to the speech asserted that Carter's policies pose the "main obstacle on the path of detente."
U.S. officials said last week the secret shaft and various electronic gear in it were discovered by workers doing remodeling. An embassy security officer reportedly crawled into the connecting tunnel and came upon a Russian scrambling in the opposite direction.
The Russians say that U.S. agents have penetrated into the neighboring building, that they have "destroyed" its heating facility and damaged "a protection system" designed to counter U.S. espionage activities.
The system "represents a purely protective measure in connection with intelligence and subversive activities conducted by American special services from the U.S. embassy building in Moscow," the statement said.
U.S. officials yesterday refused to disclose the nature of the electronic gear retrieved from the secret shaft. One of the devices was earlier described as a dish-shaped instrument believed to be a transmitter-receiver. There was no information on whether the equipment could have compromised security of the embassy.