(Reuters) - An early morning mine blast in the eastern Ukrainian rebel stronghold of Donetsk killed more than 30 people and injured 14, a local official said on Wednesday.

Approximately 70 people were working underground at the time of the explosion, a local emergencies ministry official told the Donetsk separatist press service as saying.

Previously, local officials had said 70 people were trapped underground. It was not clear if some of them were now being listed as killed and injured.

The cause of the blast in the Zasyadko coal mine was not immediately clear.

The head of a local mining safety service Vladimir Tsymbalenko, said poisonous gases released by the explosion were being removed to clear the way for rescue workers to reach the blast's epicentre.

"According to preliminary information, more than 30 people were killed. Rescue workers have not yet come to the place of the explosion, they are removing the poisonous gas and then will go down," he said.

An explosion at Zasyadko in 2007 killed 106 people.