"We have halted production, though miners are still working in other safe parts of the mine," he told Polish TV.

Serious burns

He said around 40 miners were underground when the blast occured. About 29 escaped to the surface while the rest were evacuated by rescue workers.

But Bielecki warned the death toll could climb as several miners sustained serious burns.

Tomasz Zawadzki, a miner who was 650 metres below ground when the accident occured, told Polish television: "We've lost our colleagues, but this is our reality.

"That's how it is - we will have to come back to work in coming days."

Grzegorz Schetyna, Poland's interior minister, travelled to the area on Friday to meet families of the victims.

The blast is Polan's most serious mining accident since a methane gas explosion killed 23 miners at the Halemba mine in November 2006.

In June 2008, five miners were killed in a similar explosion in a shaft 900 metres underground near the town of Jastrzebie Zdroj.