Two employes responsible for helping to stem the poisonous gas leak that claimed as many as 2,000 lives, according to some unofficial reports, ran away rather than try to control the high-pressure burst of fumes, senior police and company officials said today.

As a toxic cloud drifted toward a densely populated slum nearby, the workers left a supervisor to fend for himself at the Union Carbide India plant's methyl isocyanate storage-tank section, said Maj. Girish K. Tiwari, a superintendent of police for the Ghopal district. The supervisor eventually was overcome by the toxic fumes while the gas continued to vent from an apparently overloaded high-pressure neutralizing tank for 45 minutes, Tiwari said.

His account was verified by V.P. Gokhale, managing director of Union Carbide India Ltd., which produces 1,400 tons of pesticides a year at its Ghopal facility, mostly for use in India.

The death toll continued to be a subject of controversy, with the United News of India putting the total at 2,000, the Press Trust of India placing it at 1,600, and officials insisting that the government had evidence of only 620 deaths.

Authorities here conceded the official toll could rise much higher, and police began house-to-house searches in some slum neighborhoods looking for victims who might have died before they were able to seek medical help.

In the United States, a leading authority on the health effects of methyl isocyanate said the death toll could easily climb "several times higher" during the next few weeks as more of those exposed succumb to secondary effects.

Yves Alarie, who has studied the chemical's effects on laboratory animals at the University of Pittsburgh School of Public Health, said it was likely that the first to die in India suffered the equivalent of a massive asthma attack as the air passages in their lungs swelled shut. Next to fall were those who received lower doses that caused fluids to accumulate in the lungs, leading after a day or two to the equivalent of drowning. In the coming weeks, Alarie said, people who received relatively light doses are likely to succumb to ordinary respiratory infections that, in damaged lungs, are often fatal.

Gokhale, noting that the circumstances of the gas venting will be under court jurisdiction, would provide no details of the actions of the two workers, who are being sought by police.

Tiwari said the blame extends further than the two workers who allegedly fled, because "these two were from the labor class. We hold the manager and plant supervisor responsible. We hold the entire management responsible."

Five supervisory employes at the plant, including the works manager and assistant works manager, have been arrested on negligence charges. The supervisor who allegedly was abandoned by the two workers was identified by Tiwari and Gokhale only as Shetti, his last name. Shetti is under police guard at a hospital here.

The gas leak, according to Indian government officials and Union Carbide India engineers, began with a buildup of pressure in an underground storage tank containing liquid methyl isocyanate. The compound is used in combination with other substances to create a commonly used pesticide called carbamate, which sells in the United States under the brand name Sevin among others.

Chemical engineers said that the pressure buildup, possibly caused by a chemical reaction, automatically diverted the gas to a "vent scrubber" designed to neutralize the gas with a caustic wash.

Union Carbide engineers said the diversion from the holding tank was carried out smoothly, but for reasons that still are not clear the neutralizing tank was unable to accommodate the sudden overload, and a backup escape valve released the fumes into the air.

"The neutralizing process requires a certain amount of residence time for the gas to be run through all the scrubber operations. That time just was not there. When gas gets under high pressure, it escapes at a high velocity," said K.S. Kamdar, vice president for agrochemicals.

Kamdar said that Shetti tried to cool the 50-foot-tall stainless steel tank by hosing it with water, but apparently it was too late. The valve of the neutralizing tank opened, he said, and the gas escaped into the air.

As the death toll from one of the worst chemical plant accidents on record continued to mount, information began to surface of misjudgments or omissions that could have resulted in a lower death toll after the poisonous gas began to leak, officials said.

Tiwari said that at about 1 a.m., the police began receiving complaints from residents living near the pesticide plant. He said that when the police telephoned a factory official, the official said, "Sahib, there is some slight leakage. We are trying our best to control it."

"The factory did not call us. We called the factory," Tiwari said.

Gokhale, in an interview, said, "One of the government administration called the plant manager's house and said that we are hearing complaints of a leakage. That's how the plant manager became aware of it." Gokhale said the alarm was sounded at 1 a.m. Some residents of the Jai Prakash neighborhood of shanties that abuts the plant said they did not hear the factory siren until 1:30 a.m.

When asked why the neighborhood of several thousand lean-to shanties was allowed to grow so close to a plant storing tons of lethal gas, and whether Union Carbide India had warned the government of possible danger to the inhabitants, Gokhale said, "If we said we did warn the government, we would be blaming the government. If we said we didn't we would be blaming ourselves . . . . There will be blame found. But we don't want to get into finger-pointing."

Tiwari said that Jai Prakash, where most of the victims lived, grew haphazardly in 1977 on government-owned land as construction laborers and their families built shanties close to the factory project where they were working. The police superintendent said that subsequently the Madhya Pradesh state chief minister, Arjun Singh, granted a patta, or form of habitation rights, to the squatters on assurances by Union Carbide India officials that the new plant was safe. "Nobody knew there was a danger," Tiwari said.

Singh said that he also did not anticipate the danger to the slum dwellers.

Asked whether the slum will be evacuated now, Singh said, "There is no question of evacuation. I don't think we should think in those terms. People are there. I don't think we should panic."

He said the government's first priority is to destroy the remaining poisonous methyl isocyanate in the storage tanks. When that is done, he said, "the factory will never be allowed to operate there again." Removal of the plant, Singh said, is "an irrevocable decision." Union Carbide India Ltd., 50.9 percent of which is owned by the U.S. parent firm, based in Danbury, Conn., produced nearly $210 million in all of its India-based operations last year, company officials said.

Singh, who put the official death toll in the disaster today at 620, said the number of persons treated for effects of the gas -- mainly pulmonary edema and ulcerated eyes -- had climbed to more than 50,000.

Hospitals and makeshift clinics were still crowded today with people seeking treatment, and throughout Bhopal, a city of 700,000, people could be seen holding rags to inflamed eyes as they walked or were led to government clinics set up in tents by the roadside. Physicians at the Hamidia Hospital said that if victims were not treated time, exposure to the gas could cause blindness.

Relief workers and volunteers were waging an uphill battle to cremate or bury victims of the gas leak, but, Singh noted, many of the impoverished and low-caste persons normally hired for such jobs were victims themselves, thereby requiring the recruitment of volunteers from outlying areas.

Cranes and trucks were being pressed into service to remove hundreds of carcasses of poisoned cattle.

Samples of vegetables from farms near the pesticide plant were flown to New Delhi today for chemical analysis to determine whether they have been affected by the toxic fumes. Similarly, veterinarians have been checking the flesh of animals that died following the accident to see if it is contaminated.

Vasant Sathe, Indian minister of chemicals and fertilizer, told reporters here today that in the future factories capable of emitting toxic gases would not be allowed to be built in congested areas.

In response to reporters' questions, Sathe said the Indian government would demand compensation from the U.S.-based Union Carbide firm at the same level as would be paid in the United States. The families of victims of disasters in India are usually paid the equivalent of about $500.

The Associated Press reported from Danbury, Conn.:

A Union Carbide Corp. official denied an allegation that the company failed to ensure safety standards like those for U.S. plants at the pesticide factory in India.

The charge was made yesterday by Sathe, who also alleged that Union Carbide kept the Indian government "uninformed about the safety devices in the factory."

At a news conference in Danbury, Jackson B. Browning, Union Carbide's director of health, safety and environmental affairs, denied both charges.

"The Indian plant was designed and built by American nationals," Browning said. "As to the standards in effect in this country and those in effect in Bhopal, they are the same.

"We are confident that, to the best of our knowledge, our employes in India were in compliance with all laws, and we are satisfied with the facilities and the operation of them."