Coal mining authorities in Poland say that contact has been lost with 10 miners following an underground tremor and methane gas discharge at the Borynia-Zofiowka mine in the south of the country.
The accident at 3.40am on Saturday occurred some 900 metres underground.
It was the second colliery accident in just four days in the coal mining region around the town of Jastrzebie-Zdroj, near the Czech border.
Repeat methane blasts since Wednesday at the nearby Pniowek mine have killed five and left seven missing and injured dozens. Both mines are operated by the JSW company.
The company said that 52 workers were in the area of the tremor at the Borynia-Zofiowka mine and 42 of them were able to leave the shaft on their own. A rescue operation has been launched for the 10 missing miners.