He told a German newspaper he had been recruited at the age of 17 into the Waffen SS Frundsberg Panzer Division and served in Dresden.

He told the Frankfurter Allgemeine Zeitung, "My silence over all these years is one of the reasons I wrote this book [Peeling Onions]. It had to come out, finally."

The SS began as a private bodyguard for Nazi leader Adolf Hitler and grew into an elite fighting force responsible for the death camps.

Grass, who was born in 1927, is widely admired as a novelist and an outspoken peace activist.

At the time he did not feel ashamed to be a member, he said but he added, "Later this feeling of shame burdened me."

Grass's memoir of his wartime youth is due to be released in September.