The company said the Roytown and Hart surface operations in Somerset, Somerset County, would close their doors because of a drop in coal demand and the tightening of US Environmental Protection Agency regulations.

Both operations are about 60 miles to the southeast of Pittsburgh.

Company president and chief executive officer D Lynn Shanks said the escalating costs of operation as well as “uncertainty” generated by the advancement of the EPA’s outlines had “created a challenging business climate for the entire coal industry”

PBS did not indicate if the closures were temporary or permanent.

Company spokeswoman Lori Mason told the Associated Press that it had been hurt by the global steel market.

“The steel market has been sluggish, but we believe there is going to be a pickup” next year, she said, adding that the miner was continuing to make operational investments.

The furloughs come after the company’s July confirmation that it would lay off 225 of what at the time was a workforce of 1000.

Officials blamed market demand and increased costs to meet new EPA guidelines for those cuts.

“The decision to idle our surface mine operations is a difficult one but in an effort to manage our inventory and to balance coal production with expected customer demand and shipping schedules we are faced with making adjustments which, unfortunately, will impact our workforce,” Shanks said at the time.

“Both the foreign and domestic coal markets remain soft due to weak economic growth and activity.

“Additionally, the escalating costs and uncertainty generated by recently advanced EPA regulations and interpretations have created a challenging business climate for the entire coal industry.”

Mason told local news station WJAC in July that it had waited as long as it could to take action and respond to the downturn.

“Because we're doing this we're going to be very well situated when the market rebounds," she said.

Following the closure of Roytown and Hart, the producer will be left with just over half of its crews, or about 600 employees.

Russia-based Severstal owns PBS Coals and RoxCoal, both of which focus on Pennsylvania operations.

Severstal acquired PBS in November 2008, making it a wholly owned subsidiary.