Rescuers searching for survivors in a coal pit accident in the south of Poland have found two dead and located two more, but another six miners are still missing, the mine owners JSW said on Sunday.

"The rescuers have carried a second miner... to their base where the doctor pronounced him dead. He has now been brought above ground," the company said in a statement. 

"Another rescue team is going to find the others they were able to locate" late on Saturday, despite not having been able to establish contact. 

"Once the two other miners have been taken out, the rescuers will continue... to look for the other six still missing," JSW said. 

The accident on Saturday - the second such incident in Poland last week -- happened at the Zofiowka mine in the south.

Poland, which relies on coal for some 70% of its power, has had several other mining disasters in recent years. 

A tremor shook the Zofiowka pit at 3.40am on Saturday, 900 metres below the surface, sparking a methane leak. 

All but 10 of the 52 miners underground managed to make it to the surface.

JSW is also the owner of a mine in Pniowek, 230 kilometres to the south, where an accident on Wednesday killed five, including a rescuer, and left seven missing.

An initial explosion occurred shortly after midnight on Wednesday at a depth of 1,000 metres.

A second shook the site while rescue workers were helping the victims of the first.

Twenty people were hurt, including six with serious burns. The search for the seven people missing was called off on Friday after a third blast made conditions in the pit too dangerous, JSW said.