The survivors said on Wednesday they would ask the European Court of Human Rights (ECHR) to decide whether Russia broke the law by ending the stand-off with an opiate gas that killed nearly 130 people.
Lwayers for the survivors said Russian prosecutors had blocked all their inquiries into details about last October's incident and that they had no alternative but to appeal to the court in Strasbourg.
"The authorities failed to administer proper medicine (to the survivors) and at the same time are refusing to investigate why this was the case," said Yelena Liptser of the Civil Alliance of International Defence, a Russian group specialising in appeals to the ECHR.
"These are two crimes that we are pursuing," she said. "We will file a formal lawsuit within a month."
Rights groups and many of the survivors are still demanding answers from Putin and Russian prosecutors about the incident.
"These are two crimes that we are pursuing. We will file a formal lawsuit within a month"
Civil Alliance of International Defence
They say the gas reportedly used in the attack - one based on the anaesthetic fentanyl - is not administered in compliance with Russian legislation.
They also accuse authorities of being responsible for some of the deaths because they failed to tell doctors treating the victims what type of opiate has been used.
"Although a year has passed, the powers that be are trying to hush up the truth about how the hostages were treated and who was responsible for the deaths of 129 people," said Lev Ponomaryov of the For Human Rights group and a former liberal lawmaker.
About 40 Chechen rebels stormed the Moscow theatre on 23 October 2002 and took around 800 people hostage while demanding an end to President Vladimir Putin's war in the separatist southern republic.
Putin refused to negotiate with the fighters and the conflict was resolved on 26 October when Russian special services pumped a powerful gas into the building to stun the hostage-takers before storming it.
Most of the 129 hostages who died were killed by the gas.
About 40 hostage-takers who staged the attack also died - those who survived the opiate attack were shot dead by the storming troops.