More than 330 hostages were killed over the course of the siege in September 2004
A European court has found "serious failings" in Russia's response to the Beslan school attack which left hundreds of people dead.
About 30 Chechen militants seized the school in the southern town of Beslan in September 2004, taking hundreds of hostages.
The siege ended two days later when Russian troops stormed the school.
More than 334 hostages were killed over the course of the siege. Around half of the victims were children.
The European Court of Human Rights said Russian authorities had failed to take the necessary preventive measures - despite having had information that an attack had been planned in an area - and used excessive force.
The court also noted that security at the school had not been increased.
In their judgement, the judges wrote: "The Court held that the Russian authorities had failed to plan and conduct the rescue operation so as to ensure that the risk to life was minimised.
"[An] absence of formal leadership resulted in serious flaws in the decision-making process and coordination with other agencies. Among other things, it affected the authorities’ ability to coordinate the medical, rescue and fire-fighting response."
They also state: "The Court concluded that the use of lethal force by security forces had contributed, to some extent, to the casualties among the hostages."
The court's findings were rejected by the Kremlin.
"It is impossible for us to agree with this phrasing," said spokesman Dmitry Peskov. "Such phrasing for a country that has suffered an attack is absolutely unacceptable."
The Strasbourg court ordered Russia to pay €2.9m in damages and €88,000 in legal costs.
The massacre was one of a string of brutal attacks Russia suffered in the 1990s and 2000s stemming mainly from an insurgency in Chechnya.
The militants seized the building on the first day of the school year.
They rigged the gymnasium of the school with explosives and packed more than 1,100 hostages inside, including around 800 children, plus parents and teachers.
The militants were demanding the withdrawal of Russian troops from Chechnya.
Two days later some rebels detonated explosives during a shootout when Russian forces moved in.