Mining giant AngloGold Ashanti has been accused of responsibility for war crimes in the Democratic Republic of Congo, says Human Rights Watch.
A massive rescue operation had been initiated with 65 rescue teams and 21 medical units deployed to the scene, the statement said.
Several fatal accidents have previously occurred at the Zasyadko mine.
A gas leak in September 2006 killed 13 miners.
In 1999 an explosion claimed 50 lives, while in 2001 another explosion killed 50 people, and 20 people were killed in an mining accident in 2002.