The European Court of Human Rights has ruled that Russia failed to take measures to prevent the school siege in the city of Beslan in 2004, in which more than 330 people died.
The court has also criticised Moscow for its investigation of the case.
In the siege, Chechen separatists took more than 1,000 hostages, the vast majority of them children.
It ended when Russian security forces stormed the building. Survivors say the troops used excessive force.
No Russian official has been held responsible for the high number of deaths, which included 186 children.
Survivors and relatives say Russian officials, including President Vladimir Putin, mishandled the hostage crisis and ignored intelligence indicating that a hostage-taking scenario was being planned.BBC