Union Carbide Corp., for the first time raising the possibility of sabotage in the fatal gas leak at Bhopal, India, last December, said today the accident was caused by a large volume of water that was "inadvertently or deliberately" pumped into a storage tank containing the gas.

Releasing their internal report into the worst industrial accident in history, company officials said that between 120 and 240 gallons of water had been improperly and unaccountably introduced into a storage tank containing deadly methyl isocyanate (MIC) shortly before the accident.

The mix of such a large amount of water with the MIC and another chemical in the tank triggered a runaway reaction that leaked a cloud of MIC gas over Bhopal, killing more than 2,000 people, the company said.

"We're saying water got into the tank and we don't know how," Union Carbide Corp. Chairman Warren Anderson said. "It could have been inadvertent or it could have been deliberate. The question of sabotage will have to be answered over in India."

Indian news accounts have long speculated on the possibility of sabotage at Bhopal, with potential culprits ranging from disgruntled Carbide employes to political dissidents and foreign agents. But, despite the use of the word "deliberately," Anderson declined repeated attempts to elaborate on the likelihood of such an occurrence. He later said the word "deliberately" was not necessarily intended to imply that the water was introduced into the tank with "malice."

Anderson and other company officials also blamed the managers of the Bhopal plant for what they said were a series of "critical" violations of company safety procedures that contributed to the accident. Some of the safety violations were so serious -- such as the failure to fix a key refrigeration system that had been broken for months -- that they warranted shutting the Bhopal plant down until they were corrected.

"The operation of that plant was not in conformance with standard operating procedures," Anderson said.

Since the Bhopal tragedy, more than 35 lawsuits asking for hundreds of billions of dollars in damages have been filed against Carbide in the U.S. courts. In addition, the Indian government recently hired a Minneapolis law firm "with a view to assert claims" against Carbide in this country.

As a result of these suits and criminal actions against Carbide employes in India, Anderson said the company was confining its remarks "to what happened and not who was at fault." But while the company did not accept any responsibility itself for the disaster, it sharply criticized the actions of its Indian subsidiary, Union Carbide Ltd. of India. The Indian firm is 50.9 percent owned by its U.S. parent.

Anderson said that it was not unusual that corporate headquarters was not aware of safety violations at the Bhopal plant because it was the job of local managers to see that they were corrected.

"Safety is the responsibility of people who operate in our plants," said Anderson. "It's a local issue."

But, Anderson added, "You can't come to the conclusion that all Indians are incompetent because that's not true. We have highly competent Indians throughout the entire Union Carbide universe."

Company officials, who have previously accepted "moral responsiblity" for what happened in Bhopal, acknowledged today that they have not answered all questions about what happened, partly because their on-site investigative team of seven engineers and scientists was unable to conduct formal interviews with key plant managers who are facing criminal charges in India.

Nevertheless, they said they had learned enough to know that a lethal release "could not occur" at Bhopal's sister plant in Institute, W. Va., where the company ceased MIC production immediately after the Indian accident.

"Now, after the investigation, we are even more certain of our answer" that a Bhopal-like incident could not occur at Institute, said said Jackson B. Browning, Carbide vice president for health, safety and environmental affairs.

Carbide officials said that, assuming they get approval from the Environmental Protection Agency, the company intends to resume MIC production at Institute during the first week of April. Anderson noted that such an early return to production was needed to meet Carbide's commitment to farmers and others dependent on the pesticides made from MIC.

But Rep. Henry Waxman (D-Calif.), chairman of a House health and environment subcommittee, said today that he was "troubled" by the idea of the company resuming production at the facility and that he may try to block it.

"I've come to the point where I don't think we can take Union Carbide's word for what happened in India and that it couldn't happen here," he said. "They have issued so many contradictory statements . . . . I don't think that Union Carbide should be the sole judge of whether to open that plant."

Waxman also said that the company's introduction of the possibility of sabotage seemed "to be a way of separating themselves from what happened."

Among the most serious violations at the Bhopal plant cited by Carbide officials involved a refrigeration unit crucial to controlling chemical reactions in the storage tank. The unit had been out of operation for five months before the leak and had still not been fixed, according to Ron Van Mynen, corporate director of health and safety and the chairman of the investigating team.

In addition, a flare tower designed to burn off gases vented from the plant, including emissions from the MIC storage tanks, also was shut down and was undergoing maintenance work at the time of the leak.

Workers who monitored the storage tank were not aware of a dangerous buildup of pressure in the tank, possibly because temperatures inside the tank were apparently not logged between shifts -- yet another violation of safety procedures, Carbide said. In addition, an alarm that had not been reset failed to sound a warning of the rapid rise in temperature in the tank, Van Mynen said.

Anderson said these safety lapses were "in total disregard" of the company's procedures.