A 55-year old man is being questioned on the suspicion of gross negligence manslaughter after the deaths of four miners in the Swansea Valley.
The man, who remains nameless, is under police custody at the Port Talbot police station.
The tragedy, where four miners died having become trapped in the Gleision colliery, has affected the local community deeply but this news will at least be welcome news to the families concerned who were notified earlier this morning.
Detective Chief Inspector Dorian Lloyd, of the South Wales Police specialist Crime team said: "The arrest follows consultation between the South Wales Police, HSE and 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."
He said they would do everything possible to fully understand how the four men lost their lives.