PITTSBURGH — A southwestern Pennsylvania coal company is idling two of its mines and laying off 138 workers, but it hopes things will get better next year.

PBS Coals’ announcement Thursday comes on the heels of a July announcement that it had laid off 225 workers. Before those layoffs, PBS had roughly 1,000 employees.

Now, the Roytown and Hart mines about 60 miles southeast of Pittsburgh will be idled, too, leaving the company with about 600 employees.

PBS Coals spokeswoman Lori Mason said the Somerset-based company has been hurt by the weak global steel market. PBS is owned by Russian steel giant OAO Severstal, and almost all its coal is used to produce steel.

“The steel market has been sluggish, but we believe there is going to be a pickup in that” in 2013, Mason said, noting that the company is still making new investments in its operations.

The company also blamed tightening U.S. Environmental Protection Agency regulations, but competition from booming natural gas production has also played a role.