UPMC hospitals and physicians will be available to Highmark Inc. insurance customers at in-network rates through June 30, 2013, under a new agreement the warring companies announced this morning.

Citing the influence of Gov. Tom Corbett and a mediation process, the companies agreed to extend physician contracts for a year until hospital contracts expire.

In a statement, UPMC noted that the agreement also will allow time for regulators to examine Highmark's acquisition of West Penn Allegheny Health System.

"We are grateful to the Governor and his mediators for conducting an informed and constructive process with patient care and access the highest priority," UPMC said in its statement.

Highmark spokesman Michael Weinstein this morning said it is hoped that the stopgap measure will pave the way for a longer-term solution involving a new contract between the two healthcare giants.

"We're going to continue to work toward achieving a long-term contract with UPMC that guarantees that our members have access to all UPMC hospitals and doctors, and that's preserving provider-choice in the marketplace."

Mr. Weinstein would not disclose any details about the negotiations that led to the agreement. He would not reveal who was involved from Highmark or if there was a third-party mediator other than the governor's office.

"We're not getting into the details," Mr. Weinstein said.

He lauded the Legislature for its role in hammering out a short-term solution, citing in particular the work of state Sens. Don White, R-Indiana and Jay Costa, D-Forest Hills, as wells as state Rep. Randy Vulakovich, R-Shaler.

"The actions by the Pennsylvania state Senate and the Pennsylvania House of Representatives have been instrumental in helping to achieve the result that we have today on behalf of Highmark members because the House passed legislation, a Senate committee passed legislation, and so we're applauding those efforts in helping to achieve this result," Mr. Weinstein said.

The senators sponsored a bill that would give the Pennsylvania insurance commissioner greater authority to extend terms, by up to three years, of a UPMC-Highmark contract. Their legislation cleared a Senate committee last week.

Rep. Vulokovich's bill also empowers the insurance commissioner.

The agreement to extend physician coverage was reached during a private meeting Wednesday with a mediator assigned by Mr. Corbett.

"The governor has been working actively behind the scenes with both parties to spur negotiations and encourage them to resolve their differences," Corbett spokesman Kevin Harley said. "This is certainly a positive step for health-care consumers in Western Pennsylvania."

Mr. Harley said Mr. Corbett conducted some of those meetings himself and had staff members with him at others. He emphasized that the extension is just one step and the governor will continue to meet with Highmark and UPMC officials to get them to reach a long-term agreement.

"He won't be shy about looking for a role," Mr. Harley said.

Mr. Harley said the governor may continue to help mediate differences between UPMC and Highmark if asked.

"There are still other differences," he said. "We hope the parties continue to negotiate in good faith."

Highmark and UPMC are nearing the end of a 10-year reimbursement contract that sets the rates Highmark pays for UPMC services and gives Highmark's millions of policyholders wide access to UPMC facilities.

Highmark says it wants to negotiate a new contract with UPMC. UPMC says it won't and can't do so now that Highmark is in the process of acquiring the No. 2 health system in the region, the financially troubled West Penn Allegheny Health System.

The announcement today is a change for UPMC, but not for Highmark.

Highmark had contended that its contract with UPMC include a "run-out" clause that maintains the status quo through June 30, 2013, but UPMC contended that Highmark subscribers would lose access to in-network rates to UPMC physicians on June, 30, 2012.

UPMC's view of the contract was being debated in federal court in a lawsuit filed by Highmark contesting advertisements UPMC put out that said Highmark subscribers would lose access to UPMC doctors next year, not in 2013.