MOSCOW, Oct 27: Russian health officials admitted on Sunday that a gas used in a special forces operation that ended a Chechen hostage crisis had left 115 hostages dead, with dozens more seriously ill in hospital.

In a startling announcement, Moscow chief medical officer Andrei Seltsovsky said that only two hostages were shot dead by the Chechen rebels before the pre-dawn assault.

He told a news conference that 117 hostages had died so far but suggested that the toll could rise further, with 145 people in intensive care, 45 of whom were listed in serious condition, suffering from the after-effects of the powerful gas.

“Normally you don’t die from inhaling such a substance,” Seltsovsky was quoted by the Interfax news agency as saying.

But Setsovsky noted that the hostages were in weak physical condition after their three-day ordeal. In total, 646 people remain in hospital, the doctor said.

Moscow chief anaesthaetist Yevgeny Yevdokimov described the gas as a “psychotropic” substance normally used as a general anaesthetic.

In high doses, it changes the basic functions of the body, possibly leading to a loss of consciousness and impairing breathing and blood circulation, he added.

Doctors had complained that they did not know how to treat the ailing because they had not been told what gas had been used.

More than 800 people had been held hostage since Wednesday by a gang of dynamite-strapped Chechen militants who stormed into the theatre during an evening performance of a popular musical and threatened to blow up the building.

All 50 Chechen hostage-takers, including women, were killed in the raid early Saturday that President Vladimir Putin described as a success in an address to the nation.

“We achieved the near impossible, saving hundreds, hundreds of people,” Putin said. “We proved that Russia cannot be brought to its knees.”

He acknowledged the high price paid for ending the crisis, saying: “Now I want to address the families and friends of those who died. We were not able to save everyone. Forgive us.”

Russian authorities said Saturday that more than 750 people had been rescued, but since then the number of dead has continued to rise.

Anxious relatives kept vigil outside hospitals, desperately waiting to know if loved ones had made it through the ordeal.

Authorities refused to allow family members to enter the hospitals and did not provide lists of the survivors, keeping relatives in the dark about the fate of their missing children, husbands and wives.

“I appeal to everyone for help. We can’t find him anywhere,” one woman told NTV television, calling for news of here missing 18-year-old son. Kommersant newspaper said about 100 people were still unaccounted for.

According to the hostages, the rebels shot dead two men a few hours before the assault was launched.

Seltsovsky said that one of them had not died and was in intensive care.

A woman who tried to enter the theatre late Wednesday was shot dead by the Chechen hostage-takers.

A Dutch woman and a Kazakh teenager died from gas poisoning overnight, NTV channel reported quoting doctors. They were among four non-Russian hostages who have been confirmed dead, including an Austrian woman and a Belarussian woman.

The United States, which has two citizens missing and a third who is in hospital, has demanded information on the nature of the gas but has received no reply, a US embassy spokesman told AFP.