Russia's top health official said Wednesday that the gas used in the storming of a Moscow theater held by Chechen gunmen was based on fentanyl, a fast-acting opiate with medical applications, Russian news agencies reported.

Health Minister Yuri Shevchenko said the compound was an anesthetic and would not normally cause death, the Interfax and ITAR-Tass news agencies reported.

"By themselves, these compounds cannot provoke a fatal outcome," Shevchenko was quoted as saying.

The announcement appeared to be an attempt to counter criticism, especially from foreign governments, that Russian officials were being too secretive and that the lack of information about the gas used in the special forces raid on Saturday may have increased the number of fatalities. At least 117 of the hostage-takers' victims were felled by the gas.

But Shevchenko said that the deaths were caused by the use of the chemical compound on people who had been starved of oxygen, were dehydrated, hungry, unable to move adequately and under severe psychological stress.

"It is precisely these factors that led to a fatal outcome for some of the hostages," Shevchenko said.

The incapacitating gas was intended to prevent the hostage-takers from triggering explosives strapped to their waists and rigged around the theater. It worked but it also knocked out most of the hostages.

On Tuesday, the U.S. ambassador to Moscow, Alexander Vershbow, said the lack of information provided by Russian authorities "contributed to the confusion after the immediate operation to rescue the hostages was over."

"It's clear that perhaps with a little more information at least a few more of the hostages may have survived," he said.

Dr. Thomas Zilker, a toxicology professor at Munich University Clinic in Germany, said Wednesday that blood and urine samples from two Germans among the former hostages showed traces of halothane, a gas used as an inhaled anesthetic. He said he believed the gas pumped into the theater likely also contained other substances.

The hostage-takers seized the theater, with more than 800 people inside, on Oct. 23. They demanded that Russian President Vladimir Putin withdraw Russian troops from Chechnya, where the most recent war began in 1999.

Meanwhile, families and friends held funerals for victims of the hostage crisis.

At a small chapel at Moscow's Kalitnovo cemetery, Vladimir Zhulyov's relatives were joined by dozens of colleagues of the cellist, who turned 46 on Oct. 23 — the same day masked gunmen interrupted a performance of the musical "Nord-Ost," taking about 800 hostages. Zhulyov played in the orchestra and died from the gas Russian authorities pumped into the theater to knock out the hostage-takers.

Zhulyov's mother, Zinaida, and his wife, Yelena, wept as his coffin was lowered into the ground under a cold drizzle.

Across the city, weeping child actors from the musical buried two of their colleagues at the Vagankovo Cemetery: Kristina Kurbatova and Arseny Kurilenko, both 13.

Russia's two houses of parliament began their sessions with a moment of silence for the victims of the theater raid.

The lower house, the State Duma, refused to consider a proposal by liberal lawmakers to form an independent commission to investigate how the hostage-takers had penetrated Moscow with large amounts of weapons and explosives and how emergency services responded to the crisis.

The upper house, the Federation Council, voted unanimously to allocate an additional 3 billion rubles (US$95 million) in budget funds to fighting terrorism, according to the Interfax news agency.

The chamber also adopted a resolution praising law enforcement agencies "that saved hundreds of people" and vowing to take all necessary measures to fight terrorism.

Russian officials have defended the rescue operation, in which the building was filled with a secret gas before special forces stormed it.

The incapacitating gas was intended to prevent the hostage-takers from triggering explosives strapped to their waists and rigged around the theater. It worked but it also knocked out most of the hostages.

In a poll of 1,600 Russians taken from Friday to Monday by the All-Russia Center for the Study of Public Opinion, 85 percent of respondents said they approved of President Vladimir Putin's actions during the crisis and 82 percent said they approved of the law enforcement agencies' actions. The poll, which had a margin of error of 3.8 percent, began before the crisis ended.

Former Soviet President Mikhail Gorbachev also praised Putin's handling of the crisis.

"In those extreme circumstances that Russia lived through, Putin acted coolly and responsibly. I know it was not easy for him. However, he could not accept the demand for capitulation," Gorbachev wrote in Wednesday's edition of the official daily Rossiiskaya Gazeta.

The hostage crisis appeared to strengthen public support for the war in Chechnya. Forty-six percent of respondents in the poll said the military should continue its campaign in the rebel region; 44 percent said officials should begin peace talks. Last month, 34 percent voiced support for continuing the war and 57 percent said talks should begin.

As of Wednesday morning, 230 rescued hostages remained hospitalized, 15 of them in serious condition, the Interfax news agency said. A total of 434 patients had been released, but many continued to visit hospitals for treatment, the agency quoted an unidentified health official as saying.

Five officers of the special forces who raided the theater were hospitalized, including two who were affected by the gas and two who were in shock, said Sergei Goncharov, head of a special forces' veterans association, according to Interfax.