The Corriere della Sera newspaper and weekly magazine Chi ran the never before published photo of Diana taken minutes after her Mercedes crashed in a Paris tunnel Aug. 31, 1997. It shows her in the back seat with her head slumped to one side and a paramedic trying to fit an oxygen mask over her face, the Telegraph reported Saturday.
"We feel deeply saddened that such a low has been reached," Princes William and Harry said in a statement. The brothers appealed "to all forms of media throughout the world to appreciate fully that publishing such material causes great hurt to us, our father, our mother's family and all those who so loved and respected her."
Chi Editor Umberto Brindani defended the photo as "touching" not offensive, the Telegraph said.
Diana "looks as if she is a sleeping princess," the newspaper quoted Brindani as saying. "I published the picture for a very simple reason -- it has never been seen before."
2014: The Year in Music [PHOTOS]