Anneliese Rothenberger, an internationally known German soprano who sang with the Metropolitan Opera in New York in the 1960s, died Monday in Switzerland. As befits a diva, her exact age was unknown; she was believed to be either 83 or 85.

The death, at a hospital near her home on Lake Constance, followed a short illness, friends told Agence France-Presse.

Throughout her career, she was widely praised for her thoughtful musicianship, skilled acting, and attractive stage presence.

She was best known for playing Sophie, the young Viennese maiden of Der Rosenkavalier, by Richard Strauss. In the view of many critics, her performance in the role was on a par with, if not superior to, that of any other soprano.

She sang Sophie in a well-regarded 1962 film version of the opera, conducted by Herbert von Karajan and also starring the soprano Elisabeth Schwarzkopf.

Ms. Rothenberger made her Met debut Nov. 18, 1960, in the role of Zdenka in Richard Strauss' Arabella. Reviewing her performance in the New York Times, Ross Parmenter wrote: "There is only one word for her. She was wonderful."

Ms. Rothenberger was born in Mannheim, Germany, on June 19. Most obituaries in the European press last week give the year as 1926; other sources, including her obituary on the website of the magazine Opera News, put it at 1924.

After retiring, she did not mind not singing, as she told the German magazine Stern in 2003:

"People in the street would say to me, 'It's a pity we can't hear you anymore,' " she recalled. "I thought, that is better than if they said, 'The old woman is still singing.' " - N.Y. Times News Service