MOSCOW — MOSCOW -- A scientist formerly connected with the Soviet Union's chemical weapons development institute says that Moscow developed a top-secret, highly lethal binary nerve gas last year, despite promises by the government of Mikhail S. Gorbachev that it had stopped chemical weapons research several years earlier.
The nerve gas is 10 times more effective at killing people than the U.S. equivalent, known as VX, the scientist, Vil Mirzayanov, said.
"Americans need to know about this," Dr. Mirzayanov said. He said he believes that only U.S. pressure can persuade the Russian military not to go ahead with production of the gas.
Dr. Mirzayanov also said he believes that only a few hundred people know of the existence of the gas.
A check of Western military attaches here found that none was aware of it. In Washington, chemical weapons control specialists, both inside and outside government, expressed surprise and skepticism at the claim.
Most would not comment for the record. However, Lora Lumpe, a chemical and biological arms control researcher at the Federation of American Scientists, expressed doubts.
"I would say it's spurious," she said. "It's hard to imagine a nerve gas 10 times more lethal than VX. I suppose it could be higher, but there haven't been many innovations."
The United States has made its financial aid to the former Soviet Union conditional in part on compliance with international arms control agreements. Several other sorely needed aid programs could be similarly jeopardized by a chemical weapons program that apparently violated the spirit of arms reduction, Ms. Lumpe said.
Dr. Mirzayanov and a colleague, Lev Fyodorov, have written an article about the secret nerve gas that is scheduled to appear in today's issue of Moskovski Novosti.
Interviewed by The Sun last night, they refused to discuss the chemical composition of the nerve gas. However, they said they were prompted to go public by fears of an environmental disaster and by a desire to expose the "trickery" of Russian military officials in charge of instruments of chemical warfare.
International negotiations on a pact to control the use of chemical weapons have not covered the components of the new gas because its existence has been kept secret, they said.
From 1965 until January, Dr. Mirzayanov said, he worked at the secret Moscow research institute in charge of developing chemical weapons. His last job there was as chief of the department of counterespionage.
Dr. Fyodorov is a professor of chemistry at the V. I. Vernadski Institute in Moscow who has become an environmental activist.
Even as then-Soviet Foreign Minister Eduard A. Shevardnadze was proclaiming in the late 1980s that the Soviet Union was unilaterally halting research and production of chemical weapons, work on the new nerve gas went ahead, the scientists said.
It appears that Mr. Gorbachev was aware of the project, although they believe that Mr. Shevardnadze was unaware of it.
They said the program was directed by Viktor Petronin, head of the institute, with oversight by Gen. Anatoly Kuntsevich, who was vice commander of Soviet chemical forces and is now an adviser to President Boris N. Yeltsin on biological and chemical disarmament.
Those two men, along with General Igor Yevstavyev, General Kuntsevich's successor, were secretly awarded Orders of Lenin by Mr. Gorbachev in April 1991 for developing the nerve gas, Dr. Mirzayanov said.
"Gorbachev knew everything about the chemical weapons program," Dr. Fyodorov said.
They were less certain how much Mr. Yeltsin might know about the new gas.
The question of chemical weapons dragged on throughout Mr. Gorbachev's tenure, even as work on the new gas proceeded.
Following Mr. Shevardnadze's proclamation renouncing chemical-weapons research, Mr. Gorbachev signed a treaty with the United States limiting chemical-weapons stockpiles in 1990, but the treaty has yet to be ratified.
Russia is one of more than 30 countries, including the United States, that agreed on September 3 in Geneva to outlaw the development and stockpiling of chemical weapons. But the Chemical Weapons Convention, as it is called, is not yet legally binding. It requires the signature of at least 65 countries to make it legal, said Sharon Basso, spokeswoman for the U.S. Arms Control and Disarmament Agency.
Dr. Mirzayanov said last night that chemical-weapons stocks in the former Soviet Union total about 60,000 tons, 10,000 tons over the limit agreed to with the United States. Officially, the figure given is 40,000 tons.
Like all binary nerve gases, the new gas is absorbed through the lungs or skin and interferes with the nervous system, leading to paralysis. Nerve gas is by far the most lethal chemical weapon. Dr. Mirzayanov said that tolerance for the new Soviet gas is one-tenth the tolerance level for other nerve gases.
Initial tests of the gas were carried out in Shikhani, near the Volga River city of Saratov, the two scientists said. Full testing was conducted as recently as this January in the Nukus region of Uzbekistan, south of the Aral Sea. Apparently, the leaders of Uzbekistan, by then an independent nation, were unaware of the tests.
The components of the gas are manufactured at the Khimprom (or Chemical Industry) plant in Volgograd, the scientists said. The components are easily and quickly manufactured, and are kept separate until they are loaded onto a rocket for firing into a battlefield.