Berlin ? German novelist Guenter Grass admitted in an interview that he served in the Waffen SS, the combat arm of Adolf Hitler’s dreaded paramilitary forces, during World War II, a German newspaper reported Friday.

Grass was asked why he was making the disclosure after so many years during an interview with the Frankfurter Allgemeine Zeitung, in which he discusses his new memoir about the war years to be published next month.

“It weighed on me,” he said. “My silence over all these years is one of the reasons I wrote this book. It had to come out, finally.”

The Frankfurter Allgemeine Zeitung ran excerpts of the interview with the Nobel Prize winner on its Web Site, ahead of a fuller version in Saturday’s newspaper.

Grass, 78, is regarded as the literary spokesman for the generation of Germans that grew up in the Nazi era and survived the war. He won the Nobel Prize for Literature in 1999 for works including his 1959 novel, “The Tin Drum,” made into a Oscar-winning film in 1979. He has long been active in left-wing politics as a sometimes-critical supporter of the Social Democratic Party and is regarded by many as an important moral voice who has opposed xenophobia and war.