Some victims of a clash between Georgian protesters and Soviet troops were poisoned by an "unknown chemical substance," the official government daily Izvestia reported Wednesday.

Izvestia quoted a commission investigating the April 9 clash, which left at least 20 pro-independence demonstrators dead in the Georgian capital of Tbilisi.The report followed widespread allegations that poison gas was used to crush the demonstration.

The Georgian health minister, Irakliy Menagarishvili, told Izvestia the country's leading toxicologists believed the substance used on protesters had "an irritating and atropine-like effect."

Atropine is a poisonous crystalline alkaloid that in large doses can induce nerve paralysis and delirium. It can cause death through combined cardiac and respiratory failure.

But a Foreign Ministry spokesman, Yuri Gremitskikh, asked at a briefing Wednesday whether nerve gas was used, said that was impossible because it is a "combat weapon."

Izvestia did not specify how many of 138 patients still hospitalized Tuesday had symptoms of poisoning, nor did it say if any of the deaths were caused by chemicals.

Georgian activists say several people have died from the effects of poison gas. They also charge that military authorities refused to identify the substance or tell doctors how to treat affected patients.

The Communist Party daily Pravda quoted an Interior Ministry official Wednesday as saying soldiers used tear gas in the clashes. It said the official, who was not identified, made the acknowledgement on Georgian state television.

"Unfortunately, this crucial admission came several days late and was made only after the level of passions had reached the highest degree," Pravda said.

But Pravda also quoted a military spokesman as saying troops could not have used tear gas because it is not part of their standard equipment.

Six newly elected deputies to the Congress of People's Deputies called Wednesday for the Soviet Union to develop better laws to control troops and public officials to prevent a repeat of the tragedy.

The six, whose joint letter was published in the weekly Moscow News, had just returned from a trip to Georgia.

Under the headline, "What has happened once should not be repeated," the letter called for material gathered by a commission investigating the incident to be released to the new Congress of People's Deputies, which meets May 25.