Turkey mine blast caused by 'negligence': police report
The blast ripped through the mine near the small coal town of Amasra on northwest Turkey's Black Sea coast on October 14.
The concentration of methane in the mine exceeded the warning threshold of one percent on 85 occasions on the day of the accident, the report said.
A mine employee said he was unable to reach the miners to warn them in the minutes before the explosion, citing telecommunication dysfunction and understaffing.
"Upon review of the overall operation (of the mine), it is possible to speak of a chain of negligence," said the 240-page police report.
Failures in the ventilation system may have led to a build-up of methane gas.
A new ventilation system was supposed to have been delivered in March, but the contracted supplier requested a delay, which expired on November 6.
"The prevalence of rule violations and failure of supervision have long allowed a lack of discipline in the company, generating apathy, especially in occupational health and safety", the report said.
The authors interviewed a total of 350 people, including survivors of the accident, mine employees and managers, and families of the victims.
Eight people have been formally charged in connection with the disaster, including the manager of the mine and several of his deputies.
President Recep Tayyip Erdogan pledged a full inquiry into the blast, saying those responsible would not "be spared" but has also said he believes such incidents are the result of fate.
Turkey suffered its deadliest coal mining disaster in 2014 when 301 workers died in a blast and ensuing fire that brought down a mining shaft in the western town of Soma.