At least 25 people have been arrested in Turkey following the May 13 mining disaster in Soma that killed 301 people. Three people had been charged with manslaughter.

Turkey's Dogan news agency reported among those arrested on Sunday were the general manager Ramazan Dogru and the mine's operations manager Akin Celik.

"We have all worked very hard. I have not seen such an incident in 20 years," Celik said on Friday.

They are facing charges of causing multiple deaths and injuries through negligence. If found guilty, they face three to 15 years imprisonment, based on Turkey's penal code.

Energy Minister Taner Yildiz earlier said there were 787 people inside the mine when the blast occurred. Most of the victims died of carbon monoxide poisoning.

"I was very sad when I came here and I am still very sad," he said on Sunday.

The Milliyet newspaper, citing a preliminary expert report on the accident, said the mine had violated several safety regulations, including ceilings made of wood instead of metal as well as a shortage of carbon monoxide detectors.

The report suggested the disaster could have been caused by coal heating up after coming into contact with air.

The AP reported that on Saturday the bodies of the last miners trapped underground were recovered and the mine's entrance was sealed with bricks.

"Accidents can happen of course," a mourner in Soma told Reuters, "but it's an accident when one person, two people die. When 300 people die, it's not an accident anymore."

"My only wish and battle will be to make sure Soma is not forgotten," a written note said. It was signed only "your brother."