Five officials including the Operations Manager, Akin Celik of the mining company at the centre of last week’s disaster in Turkey have been detained by police.
They are facing charges of causing multiple deaths though negligence.
A prosecutor revealed they were among 25 people who have been questioned about the country’s worst ever mining accident.
Meanwhile there have been more demonstrations in Istanbul with protesters accusing mine owners of ignoring safety standards for profit.
Many in Turkey blame the government for privatising the industry.
One demonstrator said: “Today we gathered here to remember the miners who died in Soma. A period of national mourning has been declared throughout the whole country. However, we think that this s not enough. It should also be seen as the beginning of a struggle.”
Investigators now think over heating coal may have caused the fire and explosion which sent carbon monoxide gas through the mine’s tunnels in Soma, claiming 301 lives.
While the last of the dead were buried on Sunday the whole area around the mine was closed off. There are suspicions that the true death toll is not being revealed due to the employment of illegal workers.