The House Intelligence oversight subcommittee accused the Soviet Union yesterday of covering up the facts about an anthrax epidemic at Sverdlovsk in April 1979.

On the basis of secret and open hearings, the subcommittee concluded that the Soviet explanation that people died in Sverdlovsk from eating meat poisoned with anthrax is "incomplete at best and at worst a fabrication."

What really happened, according to the subcommittee report and interviews with U.S. intelligence officials, is that an explosion at Military Compound 19 at Averdlovsk blew a could of antrax spores into the open air. That compound has long been suspected of germ warfare activity by U.S. intelligence.

A south wind took the deadly antrax spores to the outskirts of Sverdlovsk, a city of 1.2 million 875 miles east of Moscow. U.S. oficials estimate that as many as 1,000 people may have died from breathing in the spores.

Subcommittee Chairman Les Aspin (D-Wis.) said "all arms control conventions" are threatened by the Sverdlovsk cover-up.

Rep. John Ashbrook of Ohio, ranking Republican on the subcommittee, said that Sverdlovsk proves that the United States should not sign any treaties with the Soviet Union "unless they are self-enforcing or if we have the capability to fully monitor them."

On the basis of reports from persons inside the Soviet Union at the time of the epidemic and other evidence, U.S. intelligence officials have concluded that the symptoms displayed by the afflicted Russians at Sverdlovsk could have come only from breathing in anthrax germs, not from eating them in diseased meat, as Moscow said was the case.

By calculating how many anthrax spores it would take to kill the 40 to 1,000 Russians who are believed to have died at Sverdlovsk from the anthrax, U.S. intelligence officials believe the quantity far exceeded the amount needed for the laboratory experiments allowed under the 1975 biological warfare treaty.

One U.S. intelligence estimate is that 5,000 to 20,000 antrax spores were released into the open air at Sverdlovsk. However, as the subcommittee noted in its report yesterday, no U.S. intelligence agency has made the corporate judgement that the Soviets definitely violated the treaty.

The 1975 treaty, signed by the United States, the Soviet Union and 111 other countries, prohibits the production of anthrax or any other biological agent for germ warfare. However, laboratory quantities of such germs can be produced to enable a nation to develop defensive measures or conduct peaceful experiments.

The subcommittee in its report noted that the 1975 treaty did not set a specific limit on how much antrax or other biological agents could be produced before the quantity would amount to a violation. Therefore, said the subcommittee, it would be difficult to prove on the basis of current information whether the Soviets violated the treaty or not.

This leaves it to the nations that signed the treaty to judge "whether the epidemic in Sverdlovsk demonstrates a Soviet violation," the subcommittee said.

It said it had looked into reports that the Carter administration had suppressed evidence and hampered probes by U.S. intelligence agencies of the Sverdlovsk epidemic for fear the findings would keep the the strategic arms limitation treaty (SALT II) from being approved by the Senate.

Concluded the subcommittee: "There is no persuasive evidence to support allegations that the U.S. government suppressed intelligence about the outbreak of anthrax in Sverdlovsk, or that it delayed acting on this matter out of concern for SALT II or any other political motive."

Speaking for himself, Aspin said, "The evidence is fairly good that the Soviets have cheated on the treaty dealing with biological weapons. That combined with the lousy way this has been handled by the administration threatens not only this treaty but all arms control conventions."

The State Department insists that it is pressing the Soviet Union to disclose the full story on Sverdlovsk but is trying to do it within diplomatic channels rather than publicly. However, the department concedes that it has not yet received satisfactory replies to its questions about the epidemic.