Updated story

The Cleveland Clinic has performed a groundbreaking transplant of a human face on a patient who was disfigured by traumatic injury.

The operation took place in recent weeks, after years of research and planning.

The Clinic released few details this morning, but the hospital scheduled a news conference for 1 p.m. Wednesday. No information was available about the patient, who the Clinic said does not wish to be identified.

The Clinic became the first U.S. hospital to approve the procedure four years ago. Dr. Maria Siemionow, director of plastic surgery research, pushed for approval and performed the operation with a team of doctors.

Doctors in France in 2005 performed a partial face transplant on a 38-year-old woman disfigured by a dog attack. It was the first such operation in the world.

The Clinic operation is said to be a near-complete facial transplant. The operation requires taking mask-like facial tissue from an organ donor.

Siemionow has conducted extensive research transplanting faces and limbs of laboratory rats.

She had reviewed dozens of potential patients in recent years.

Facial transplantation has raised ethical debate because of questions whether patients should be subjected to the risks for an operation that is not life or death. The risks include failure of the transplanted tissue and complications from anti-rejection drugs.

Siemionow in 2004 argued her case before a Clinic board that reviews experimental procedures. She said the choice should be made by the patient, following a detailed psychological evaluation.