A man is being held in custody at Port Talbot police station, Wales, under suspicion of gross negligence manslaughter following the deaths of four men in the Gleision mine.
The 55-year-old man is thought to be the mine manager, Malcolm Fyfield, who was also injured during the incident in the mine which killed the four men.
On 15 September Philip Hill, Charles Breslin, David Powell and Garry Jenkins died when they became trapped in the mine when it flooded. Attempts were made to rescue the men from the mine in the hope that they might still be alive, but the four men were dead when their bodies were found.
Another three men escaped with injuries.
The circumstances surrounding the men's deaths are currently under investigation by the Health and Safety Executive and South Wales police. Police have said that the investigations could take up to three months to complete.
The mine has been closed, after an examination by the police, and it is now under the control of the Coal Authority.
Detective Chief Inspector Dorian Lloyd, leading the investigation, said: "The arrest follows consultation between the South Wales Police, HSE and the Crown Prosecution Service to review the evidence gathered to date.
"We continue to work closely with the bereaved families throughout this process and I would like to express my sincere gratitude to the communities affected by this incident for their continued support and patience.
"We will do everything possible to fully understand how these four men lost their lives."
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