At least 10 miners have been killed in an accident at a coal mine in Poland.

An explosion ripped through the Jas-Mos mine, at Jastrzebie Zdroj in the southern region of Silesia.

Officials say another 37 miners managed to escape, one of whom was injured.

Rescue work is continuing.

It is not known what caused the blast, which happened about 700 metres (2,300 feet) underground early in the morning on Wednesday.

Worst accident

Methane gas or coal dust were two main possibilities, said a spokeswoman.

Polish authorities have described the explosion as the worst mining accident in the country since 1987.

In that incident, 18 miners died in an explosion in Myslowice, also in Silesia.

As news spread of Wednesday's blast, flags across the region were flown at half-mast. Three days of official mourning were declared across Silesia.

The Polish Prime Minister, Leszek Miller, is also travelling to the mine after cutting short a visit to the city of Lodz.

Reform attempts

Southern Silesia is an area of heavy industry and much coalmining.

The BBC's Nicholas Walton in Warsaw says many of the mines in the area are inefficient and heavily in debt, and use outdated equipment that is often unsafe.

He says that as part of plans to restructure the industry, Poland's first private coalmine opens this month in the town of Zabrze.

Despite some opposition from the miners union, thousands of people applied for the 250 jobs on offer.