Universal Health Services Inc. added $13 million to its pre-tax reserve for the potential settlement of a longer-running civil False Claims Act investigation of billing practices at about 30 of its psychiatric facilities, the King of Prussia-based hospital company said Wednesday in its first-quarter earnings release.

The increase brings the pre-tax total reserve to $35 million.

It is not clear what government investigators are focused on. But multiple whistle blowers have alleged, among other things, that UHS used improperly licensed personnel to provide services and then billed the government. That would amount to a False Claims Act violation. The company has denied wrongdoing.

UHS warned in its first-quarter earnings release that "changes in the reserve may be required in future periods as discussions with the DOJ continue and additional information becomes available." _ Harold Brubaker