A decade after Chechen militants seized a Moscow theatre in a hostage crisis which left 130 people dead, victims' families are still seeking answers about use of a deadly gas by Russian forces to end the siege.

A total of 912 people, many of them children, were held hostage in the Dubrovka theatre for three days after coming to watch Nord Ost, a popular musical, on October 23, 2002.

The crisis ended on October 26 when Russian special forces filled the building with an unknown gas to neutralise the attackers, who had threatened to blow up the venue unless Russia pulled its troops out of Chechnya.

The effects of the gas killed 125 people, as well as the 40 attackers who were shot after being knocked out by the gas. The hostage-takers themselves killed five people.

The bloody end to the siege, two years into Vladimir Putin's presidency, damaged his image as it appeared his regime had not made it a priority to prevent the deaths of the trapped civilians.

Survivors and victims' relatives remain highly critical of how the authorities handled the crisis.

"We sat without moving in our seats right next to the stinking orchestra pit which had been transformed into a toilet," a former hostage who wanted to be identified only as Oleg told AFP.

"We were exhausted after three days without food or water," and were waiting for an assault as "our only chance to be liberated from that nightmare".

But what followed was "chaos," he said.

"Ten years have gone by, but so many questions are still unanswered," said Natalia Kurbatova, whose 13-year-old daughter Kristina, one of the young stars of the musical, was among those killed.

"Why didn't the authorities negotiate with the militants' leader, at least to let the children go? What was the gas that killed our loved ones?" Kurbatova demanded.

"I still don't know how she died," she said in an interview with AFP. Her daughter was only found in the morgue the day after the security forces stormed the building.

Medical aid to the exhausted hostages who inhaled the gas was poorly organised, said survivors, with most of the deaths resulting from suffocation rather than from explosions or gunshots.

Russian courts however have systematically rejected lawsuits from the former hostages, who have blame the authorities and demanded compensation.

Last December, the European Court of Human Rights ordered Russia to pay 1.25 million euros ($1.6 million) to 64 claimants, including ex-hostages and relatives of those killed during the siege.

"The gas didn't kill people right away, and many people died because they weren't properly tended to," said lawyer Igor Trunov, who represented the Nord-Ost victims in court.

"The doctors didn't know the composition of the gas. To this day it is classified. There wasn't enough of the antidote. The ambulances didn't have access to the building, and the hospitals weren't ready to accommodate so many ex-hostages."

While the Strasbourg court did not criticise Russia's use of force and the noxious gas, it did highlight the lack of preparation for the rescue operation.

The European court ordered Russia to reopen its investigation into the victims' deaths and possible negligence by officials, but Moscow's powerful Investigative Committee has refused to do so.

Moscow has experienced more horrifying attacks since Dubrovka. A 2011 suicide bombing in its main Domodedovo airport killed 36 people and a double suicide bombing in the metro in 2010 killed 40.

A recent poll by the independent Levada Centre pollster found that 53 percent of Russians expect more acts of terror and hostage-takings.

"The main way to protect ourselves from attacks is the work of the special forces, using agents to infiltrate terrorist networks to prevent attacks," said military analyst Alexander Golts.

"But I wouldn't say Russia's special forces have advanced far on that front," he added.

[Image via Agence France-Presse]