The contract dispute between Northern Light Health and Anthem Blue Cross Blue Shield heated up on Friday, with the hospital system’s president responding to accusations from the insurer about the status of the talks.

The crux of the negotiations is how much Anthem would pay Northern Light’s health care providers.

The two sides are in a formal mediation, but Anthem has accused Northern Light of walking away from negotiations. The hospital system disputed the claim and said it is committed to reaching an agreement.

If the two sides fail to reach an agreement, Northern Light’s health care providers would be out-of-network for about 30,000 Anthem patients in Maine. That would increase out-of-pocket costs for patients insured by Anthem if they continue to get health care from Northern Light. The state’s second-largest hospital system, it operates Eastern Maine Medical Center in Bangor and Mercy Hospital in Portland.

Earlier this week, Anthem accused Northern Light of refusing to negotiate.

On Friday, Tim Dentry, president and CEO of Northern Light Health, sent an open letter to Denise McDonough, president of Anthem Blue Cross and Blue Shield, accusing Anthem of misrepresenting the negotiations.

“At no point have we indicated that we are walking away from the mediation,” Dentry said. “In fact, we remain fully engaged, committed and ready to continue working toward a resolution.”

Jim Turner, an Anthem spokesperson, said in a statement Friday that they appreciate Dentry’s offer to restart negotiations, but added that this week “Northern Light notified Anthem that they would not return to mediation unless we first agreed to a long list of contract demands they have.”

Turner said in the statement: “Our latest offer to Northern Light Health would pay them fairly, in line with what we pay other health care systems in Maine.”

Negotiations stalled in August, only to restart under a formal mediation process a few weeks later.

If a new agreement is not reached, Northern Light says physicians and some services will be out-of-network starting Wednesday, while hospital-based services will be out-of-network starting Dec. 31. Turner said Anthem officials had requested that all health care services under the contract go out-of-network at the same time — on Dec. 31 — but that Northern Light refused.

Dentry criticized Anthem for ads on social media that he said misrepresented negotiations, including a claim that Northern Light Health requested a 30% rate increase for health care services.

“That is not true,” Dentry wrote. “These public attacks distract from the real issue: patients are not receiving the care they need, and your campaign of misinformation only worsens the anxiety patients already feel.”

Turner said Anthem stands by its statements that Northern Light has asked for a 30% rate increase.

The dispute is similar to difficult contract talks between Anthem and MaineHealth in 2022 that ultimately resulted in the contract being settled before MaineHealth patients would have been out-of-network on Anthem plans.