Nobel laureate Gunter Grass has filed a lawsuit against the publisher of his biography for claiming that he voluntarily joined the Nazis' murderous Waffen-SS unit during World War II, his lawyer said Friday.

Attorney Paul Hertin said he filed a request for an injunction against Random House — which owns the biography's publisher Goldmann Verlag — earlier this week at a regional court in Berlin. It contained an affidavit by the 80-year-old writer in which he contends he was drafted to the SS and did not join the service voluntarily, Hertin said.

It was not clear exactly what the injunction would require the publisher to do.

Grass, who won the 1999 Nobel Prize for literature and is the author of the classic "The Tin Drum" and many other writings, served in the 10th SS Panzer Division, which fought Soviet troops in Germany near the end of the war. He was wounded and then taken prisoner by U.S. forces.

His confession last summer prompted calls for him to return the Nobel Prize.