Russia ends its silence over gas that killed 120 hostages

Russia's Health Minister confirmed yesterday that the gas used to free 800 hostages in a Moscow theatre was based on a fast-acting opiate called fentanyl, ending days of confusion and secrecy that may have increased the death toll.

Yuri Shevchenko described fentanyl, which has many medical applications, as an anaesthetic. "By themselves, these compounds cannot provoke a lethal outcome," he said. But he added that 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 was the cause of death. "It is precisely these factors that led to a lethal outcome for some of the hostages," he said.

By last night, the official death toll after the special forces operation to free the theatre-goers stood at 120 hostages, all but two of them apparently killed by the gas pumped in to incapacitate 50 Chechen rebels holding them captive. Nearly all the hostage-takers were killed, many shot while they were unconscious.

Alexander Vershbow, the US ambassador to Russia, said on Tuesday that the lack of information provided by Russian authorities "contributed to the confusion" after the immediate rescue operation was over. He said: "It's clear that perhaps with a little more information at least a few more of the hostages may have survived."

Medical authorities in Moscow said 434 hostages had been allowed to go home by yesterday, but 230, including six children, remained in hospital being treated for the after-effects of the gas – 14 of them on the critical list.

Leonid Aronov, the chief doctor of Moscow's Hospital Number 13, said many hostages who had been released in recent days were returning for further treatment due to complications from the gas.

The independent TVS network said it had compiled a list of 180 hostages whose families had heard nothing from them since Chechen rebels seized the 1,100-seat Na Dubrovke theatre last week. Citing unidentified health ministry sources, TVS reported that the death toll had already risen to more than 140 hostages. "The exact number is secret," the station said.

Moscow was angered by Denmark's decision to allow a conference of exiled Chechen leaders to go ahead in Copenhagen this week. Yesterday, however, Denmark arrested Akhmed Zakayev, a Chechen rebel attending the meeting, at the behest of Russia, which said it suspected him of helping to plan the theatre siege. Denmark said he might be extradited if Russia promised not to impose the death penalty.

Mr Zakayev is a senior aide to Aslan Maskhadov, the fugitive Chechen separatist leader. Both men have condemned the raid in Moscow as the work of an extremist rebel faction.