In central Kazakhstan an explosion and fire at a coal mine owned by giant steelmaker Mittal left at least 33 dead on Wednesday.
"Thirty-three miners died, three are in intensive care and eight others are missing," said a spokesman for the rescue team at the Lenin mine in Karaganda province.
The blast was caused by a build-up of methane gas about 500 metres (1,600 feet) below ground.
In Ukraine, a gas leak killed 13 miners and made dozens sick at the Zasyadko coal mine in the southeast of the ex-Soviet republic, officials said.
"Thirteen people died, 61 were injured and hospitalised. All the others are at the surface safe and sound," Mikhailo Korsakov, a spokesman for Ukraine's emergency situations ministry in the Donetsk region said.
Kazakhstan's Lenin mine is part of a vast steelmaking complex in Karaganda and one of a number run in the former communist bloc by Mittal, the world's largest steelmaker.
"We deeply regret this tragic accident and extend our full sympathy and condolences to the families of everyone that has been affected," Lakshmi Mittal, the company's president said