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."
A body of miner is carried to an ambulance in Soma, a district in Turkey's western province of Manisa, late May 16, 2014. The death toll in this week's mining accident in western Turkey is unlikely to be more than 302 people, Turkey's Energy Minister Taner Yildiz said on Friday. A maximum of 18 people are still in the coal mine, Yildiz told reporters in televised comments on the country's deadliest ever mine disaster. REUTERS/Osman OrsalREUTERS/Osman OrsalPeople mourn at graves for miners who died in Tuesday's mine disaster, at a cemetery in Soma, a district in Turkey's western province of Manisa May 18, 2014. Turkish police have detained 18 people, including mining company executives and personnel, as part of an investigation into last week's mine disaster, CNN Turk and other broadcasters reported on Sunday. The rescue operation ended on Saturday after the bodies of the last two workers were carried out, bringing the death toll in Turkey's worst industrial accident to 301. REUTERS/Osman OrsalREUTERS/Osman OrsalA woman mourns at graves for miners who died in Tuesday's mine disaster, at a cemetery in Soma, a district in Turkey's western province of Manisa May 18, 2014. Turkish police have detained 18 people, including mining company executives and personnel, as part of an investigation into last week's mine disaster, CNN Turk and other broadcasters reported on Sunday. The rescue operation ended on Saturday after the bodies of the last two workers were carried out, bringing the death toll in Turkey's worst industrial accident to 301. REUTERS/Osman OrsalREUTERS/Osman OrsalGeneral view of a coal mine site where a fire broke out on Tuesday in Soma, a district in Turkey's western province of Manisa May 18, 2014. Turkish police have detained 18 people, including mining company executives and personnel, as part of an investigation into last week's mine disaster, CNN Turk and other broadcasters reported on Sunday. The rescue operation ended on Saturday after the bodies of the last two workers were carried out, bringing the death toll in Turkey's worst industrial accident to 301. REUTERS/ Osman OrsalREUTERS/ Osman OrsalMiners walk towards a mine to take part in search and rescue operation for their colleagues trapped in a coal mine after a mining disaster in Soma, a district in Turkey's western province of Manisa May 16, 2014. The operator of a Turkish mine in which 284 people died this week and 18 remain trapped said on Friday the exact cause of a fire was still unclear but that a build-up of heat had caused a partial collapse in the plant. Rescuers were still trying to reach parts of the coal mine in Soma, 480 km (300 miles) southwest of Istanbul, three days after a fire knocked out power and shut down the ventilation shafts and elevators, trapping hundreds underground in Turkey's worst ever mining disaster. REUTERS/StringerREUTERS/StringerA mining helmet and carnations are seen placed on the ground by demonstrators during a candlelight vigil for the victims of the Soma mining disaster in western Turkey, in Istanbul May 18, 2014. A Turkish court ordered three suspects to be kept in custody on Sunday on a provisional charge of "causing multiple deaths" in last week's mine disaster, as the last of the 301 victims were buried. The detentions came five days after a fire sent deadly carbon monoxide coursing through the mine in the western Turkish town of Soma, causing the county's worst ever industrial accident. REUTERS/Yagiz KarahanREUTERS/Yagiz Karahan
