The former chief of anesthesiology at Kaleida Health System and a prominent pediatric anesthesiologist at Kaleida are under federal investigation in connection with payments from Strong Memorial Hospital in Rochester.

Sources close to the investigation said federal prosecutors are looking into the billing practices of Dr. James Foster and Dr. Doron Feldman and their affiliation with CGF Anesthesiology Associates in Buffalo.

The investigation centers on hundreds of thousands of dollars in payments Foster and Feldman received as part of a “complex financial relationship” with Strong, according to sources.

Feldman is one of the region’s most prominent pediatric anesthesiologists and was a leading and very public advocate for keeping Women & Children’s Hospital a separate free-standing facility during the debate over its future.

“I can confirm that we’re in discussions with the U.S. Attorney’s office in Rochester about an issue that concerns my client,” said Daniel C. Oliverio, Feldman’s lawyer.

Oliverio declined to comment on what the government is looking into but said it has nothing to do with the quality of Feldman’s work at Strong or anywhere else.

“The issue has absolutely nothing to do with Dr. Feldman’s performance as a doctor or his work with federal payment programs such as Medicare and Medicaid,” he said.

Prosecutors also are investigating Foster, the former head of anesthesiology at Kaleida and now chairman of the Department of Anesthesiology at the Upstate Medical University in Syracuse.

Sources said Foster’s departure from Kaleida – he started there in 2003 and left in 2012 – had nothing to do with the federal investigation into his billing practices.

“Dr. Foster is cooperating with the government’s inquiry and we remain hopeful that the information we have provided will cause investigators to conclude that there was no misconduct,” Terrence M. Connors and James W. Grable, his lawyers, said in a statement to The Buffalo News.

Connors and Grable, like Oliverio, declined to comment on the details of the investigation but said, “Dr. Foster is among the most talented and skilled anesthesiologists in Upstate New York and he has provided and continues to provide exemplary care to all his patients.”

Before joining Kaleida as chief of anesthesiology, Foster served as chief medical officer of Children’s Hospital in Buffalo and as director of its Department of Anesthesiology.

Sources close to the investigation said the doctors’ alleged wrong-doing is limited to their work at Strong and is not connected in any way with their work at Children’s or any other Kaleida facility.

Those same sources said the investigation revolves around how the doctors were paid and their affiliation with CGF, one of the largest anesthesiology groups in Western New York and among the largest pediatric groups in the country.

CGF is not believed to be a target of the investigation.

“There’s no suggestion that CGF was billing improperly,” said Patrick J. Brown, a lawyer for the practice. “There’s no hint at all of any misbehavior on their part.”

Oliverio said the investigation, which is being handled by Assistant U.S. Attorney Richard A. Resnick in Rochester, is in the very early stages.

“We are cooperating fully and hope to have it resolved soon,” he said.

Officials at Strong declined to comment on the investigation, and a spokeswoman for U.S. Attorney William J. Hochul Jr. said his office has a policy of neither confirming nor denying ongoing investigations.