The Justice Department asked a federal court Tuesday to revoke the citizenship of an 86-year-old man, saying he served in a Nazi unit that slaughtered 17,000 Serbian civilians during World War II. Peter Egner, a native of Yugoslavia, served as a guard and interpreter with the Nazi-controlled Security Police and Security Service in Belgrade, Serbia - then Yugoslavia - from April 1941 to September 1943, said a civil complaint filed in US District Court in Seattle. Egner did not divulge that information after he immigrated to the US in 1960 and applied for citizenship, the complaint said. Instead, it said, he falsely claimed that he served in the German army as an infantry sergeant, and he was granted US citizenship in 1966. Reached by telephone at his home in a suburban retirement community called Silver Glen, Egner confirmed his identity to The Associated Press, but said he was unaware of the complaint. Asked about his alleged service with the Nazis, he said: "I have no idea what you're talking about. I'm sorry. Bye." However, the complaint said that during an interview with federal authorities in February 2007, Egner admitted that he guarded prisoners as they were being transferred to the concentration camp of Semlin and the execution site of Avala, both near Belgrade. He also reportedly admitted serving as an interpreter during the interrogation of political prisoners; the unit tortured or killed many such prisoners. The Justice Department, citing Nazi documents, said that in the fall of 1941, Egner's unit executed 11,164 people - mostly Serbian Jewish men, suspected communists and Gypsies - and that in early 1942, it murdered 6,280 Serbian Jewish women and children who had been prisoners at Semlin. Daily over the course of two months, those women and children were taken from the camp and forced into a specially designed van, in which they were gassed with carbon monoxide. "No one who participated, as we allege the defendant did, in the diabolical Nazi program of persecution is entitled to retain US citizenship," said Eli M. Rosenbaum, director of the DOJ's Office of Special Investigations. Since that office began trying to track down former Nazis in the US in 1979, it has won cases against 107 people, and in recent years more than 180 people have been barred from entering the country because of past ties to the Nazis, the Justice Department said in a news release. The Immigration and Nationality Act of 1952 provides for revocation of citizenship obtained through misrepresentation, and Egner's service with the Nazis is evidence of a lack of good moral character - a requirement for citizenship, the complaint said. Egner's attorney, Robert Gibbs of Seattle, did not immediately return a call seeking comment.