Managers of the Ukraina coalpit in Donetsk, where 35 pitworkers died in heavy fires on Sunday, have been detained and put in a detention center.
On Tuesday the governmental commission looking into the accident has detained the director, chief and production engineers.
In preliminary information, they are accused of neglect of fire safety rules.
The underground fires at the Ukraina coalpit happened in the late hours of Sunday in a drift 570 meters below the surface. At the moment, 114 pitworkers were found inside. Eighty one were taken to the surface during several hours.
Rescuers penetrated into the drift to find 35 workers choked with carbon monoxide. Their bodies were taken to the surface.
A governmental commission led by first vice-premier Oleg Dubina is working at the coalpit. Ukrainian Prosecutor General Vyacheslav Piskun headed for Donetsk on an instruction by Ukrainian president Leonid Kuchma.
Leonid Kuchma has declared Tuesday a national mourning.
The choice of the city of Helsinki is not incidental as the capital of Finland had hosted US-Soviet negotiations on the limitation of nuclear stockpiles in 1969