Russian investigators said Wednesday they had detained tycoon Mikhail Fedyayev after a blast at a coal mine in Siberia that killed 51 people last month.
The Investigative Committee, which is responsible for probing serious crimes, said it had charged Fedyayev, the owner of the SDS-Ugol company with grave "abuse of authority" and three others with violating "industrial safety" standards.
The mine is in the Kemerovo region, in southwestern Siberia.
Russia has seen a number of deadly mine blasts in recent years but this was the first time investigators detained the top owner of a mine.
Fedyayev, 59, is one of Russia's top coal tycoons and is politically well connected.
SDS-Ugol is one of Russia's largest coal producers, and last year Forbes valued Fedyayev's fortune at $550 million (488 million euros).
The general director of SDS-Ugol, Gennady Alekseyev, was detained along with Fedyayev.
His son Pavel Fedyayev is a senior ruling party lawmaker in parliament's lower house, the State Duma.
A total of 51 people — including both miners and rescuers — died after smoke filled the Listvyazhnaya mine following an apparent gas explosion in late November. It was the deadliest mining explosion over the past decade.
In the aftermath, miners spoke of frequent safety violations at the site, saying they were forced to work despite high methane concentrations.
The detentions came a day after the powerful head of the Investigative Committee, Alexander Bastrykin, met with relatives of the victims and ordered investigators to look into "the role of the mine's owners."
Earlier this month, a visibly irritated President Vladimir Putin asked Fedyayev about safety violations at the mine during a televised meeting.
"Is the board of directors monitoring what's happening in the field of safety or just counting money?" the Russian leader asked the tycoon.
The businessman insisted the company never skimped on safety measures.
"I am ready to face any responsibility," he added.
At the same meeting, General Prosecutor Igor Krasnov confirmed multiple violations at the mine, saying everything looked good at the site "only on paper."
The detentions came after investigators initially held the director of the Listvyazhnaya mine, his first deputy and several other people.
Mining accidents are fairly common in Russia as a result of poor safety standards, a lack of oversight of working conditions and ageing Soviet-era equipment.
One of the deadliest mining accidents in Russia in recent years occurred at the Raspadskaya mine in Siberia — Russia's largest coal mine — in the summer of 2010, killing 91 people and leaving more than 100 injured.