Kazakh officials have said a total of 16 prisoners were killed when inmates attempted to escape from a Kazakh prison late on July 10.
Kazakh Justice Ministry spokesman Sultan Kusetov was reported by the AFP news agency as saying the prisoners were killed during a shootout with security guards that ended with a powerful explosion.
Earlier, the Interfax news agency had reported that a group of 16 convicts described as "members of an organized crime group" were behind the escape attempt, and that several inmates died when a homemade bomb intended to blast a hole in the prison's exterior wall detonated.
The prison is located in the town of Balkhash near the city of Karanganda.
Kazakhstan has been experiencing prison unrest for several years.
The country's prison system has come under criticism from the European Union for rights abuses and other violations.
compiled from agency reports