At least 17 people have been killed in a day-long shootout between a group of prisoners attempting a jail break and security guards in Kazakhstan, officials have said.
Sixteen inmates and at least one prison guard were among those killed in the clashes, which ended with a powerful blast at the high-security prison in the southeastern town of Balkhash on Tuesday, Sultan Kusetov, the Kazakh justice ministry's prison system spokesman, said.
Kusetov said that several other guards were also wounded in the violence.
The former Soviet republic has been experiencing prison unrest for several years and has come under criticism from the European Union for rights abuses and other violations that have seen opponents of the authorities end up in jail.
Seven Kazakh guards were last month convicted of torturing nearly 30 inmates while there have also been cases of prisoners setting themselves on fire in the country's more notorious jails.
Kusetov described the incident as a failed prison break orchestrated by hardened criminals who each faced sentences of 15 to 32 years in jail.
"We fulfilled our main objective. Those who tried to flee [the jail] were unable to leave," Kusetov said.
But he could not explain the cause of the blast that he said ultimately killed the inmates.
Kusetov said a stray bullet may have hit an oxygen tank in the prison. He also added that the inmates could have blown themselves up after realising their escape attempt had failed.
The violence began with a late Sunday prison break attempt, the official said.
The group of prisoners reportedly took several hostages and barricaded themselves in a section of the jail during the clashes.
Kusetov said the prisoners involved in the jail break attempt had ties with organised crime and appeared to have received an arms shipment from their supporters.
"Logic tells you that they received these arms from criminal associates who helped them plot the escape," he said.
"Perhaps they blew themselves up because they did not want to give themselves up to the authorities.
"They knew they had injured some of our staff, that they had killed one of them. They knew that there would be no mercy for them now."