Beslan killing frenzy was sparked by accidental bomb blast in school

The bloody denouement of the Beslan hostage crisis in which more than 150 children died was triggered by a bomb going off accidentally in the school, provoking frenzied killing by the hostage-takers.

The bloody denouement of the Beslan hostage crisis in which more than 150 children died was triggered by a bomb going off accidentally in the school, provoking frenzied killing by the hostages-takers.

Alexander Torshin, chairman of a parliamentary inquiry, said the explosion "was unexpected, both to the terrorists and to the people outside". Mr Torshin has interviewed 600 people since President Vladimir Putin agreed to set up the inquiry last month.

Conflicting versions had circulated about the exact circumstances of the end of the hostage drama in southern Russia, which left a total of 331 people dead and traumatised the world as it unfolded live on television. In the chaos that followed the explosion, the hostage-takers began firing on fleeing hostages in the belief that the Russians were storming the building, prompting the security forces to move in.

The guerrillas were calling for the withdrawal of Russian forces from Chechnya, and were reported to have been ready to negotiate at the time the school was stormed.

Mr Torshin admitted that Russian security forces, who have been criticised for failing to keep the distraught and armed townspeople at a safe distance from the school building during the three-day hostage-taking, had "nothing to be proud of". He added: "If people failed professionally they will have to answer for that."

He said the explosion on the third day of the siege was "the result of a blunder", when a bomb strung up in basketball hoops fell out. "People were not focusing on that area when something dropped. Nobody needed that at that time. It was impossible to hold back the parents who broke through the security cordon searching for their children. We didn't want a battle between the parents and the soldiers." Mr Torshin, deputy chairman of Russia's upper house of parliament, also confirmed that on the first day, some terrorists objected to taking children hostage. Two women suicide bombers, who had lost their own children in the Chechen war, had their explosive belts blown up "on the orders of the commando leader".

Aslambek Aslakhanov, Mr Putin's adviser on the north Caucasus, said another member of the gang who objected to the hostage-taking was shot. "I assume those who sent them to Beslan lied to them," said Mr Aslakhanov, who was born in Chechnya but is not a member of Mr Torshin's commission. "They thought the end would be similar to what happened [in the raid on a hospital] in Budennovsk, when they were able to leave the place with a certain number of hostages. But those who sent them there understood the end would be very tragic."

More than 100 people were killed in the 1995 raid on the hospital, led by the Chechen warlord Shamil Basayev, who escaped during the botched rescue attempt by troops. Basayev has claimed responsibility for the attack on Beslan School Number One, using a gang which turned out to be far bigger than authorities initially claimed. But Mr Torshin said the claim, posted on a Chechen website, "could be a hoax".

He confirmed that 32 hostage-takers had been accounted for ­ one captured alive, 30 dead and one blown apart ­ but said that "as of today", 24 had not been identified. Police say none of the hostage-takers escaped, but Mr Torshin said: "We have to check every piece of information."

He was also reticent about the identities of the guerrillas, fearing that revealing information could trigger revenge attacks in the tinderbox region where ethnic groups are pitted against each other. He cast doubt on Russian newspaper reports which have listed those identified so far, saying only that there were hostage-takers from Chechnya and Ingushetia. He did not know whether Arabs took part. One person, with no documentation, "looks like a Kazakh or a Korean". He added: "Revenge is the thing to be afraid of. This is the Caucasus."

Mr Torshin said that "up to 500" unanswered questions remained for his committee of inquiry, comprising 10 Russian deputies and 10 senators.

Mr Torshin, who left Beslan on Monday, said his team aimed to establish the reasons for the attack, how it happened, and who was to blame.