BELGRADE, Serbia -- United States should quickly extradite to Serbia a naturalized American citizen suspected of serving in a World War II Nazi unit that killed 17,000 people, the World Jewish Congress urged Tuesday.

Accusations against 88-year-old Peter Egner, who lives in a retirement community outside Seattle, are "so horrendous that no further time must be wasted," the group said in a statement sent to The Associated Press.

"Not only the Jewish community in Serbia, but Jews worldwide expect Nazi war criminals to be tried and brought to justice, irrespective of their age," said WJC president Ronald S. Lauder. "These people may be frail, but so are many Holocaust survivors. Justice done belatedly is still better than justice not done at all."

Serbia last month formally asked the U.S. to hand over Egner for a genocide trial.

Egner was born in Yugoslavia, but emigrated to the U.S. in 1960, gaining American citizenship six years later. The U.S. Justice Department filed a lawsuit in 2008 to revoke Egner´s citizenship, which would pave the way for his extradition.

The accusations allege that Egner served as a guard and interpreter with the Nazi-controlled Security Police and Security Service in Belgrade - then part of Yugoslavia - from April 1941 to September 1943. It says Egner did not divulge that information when he applied for citizenship but falsely claimed he served in the German army as an infantry sergeant, and was granted U.S. citizenship in 1966.

Egner has denied any knowledge of the Einsatzgruppe unit that rounded up Jews, political prisoners and other enemies of the Third Reich after Hitler´s attack on the Soviet Union in the early 1940s.

The U.S. Justice Department, citing Nazi documents, said in the fall of 1941, Egner´s unit executed 11,164 people - mostly Serbian Jewish men, suspected communists and Gypsies. It also said in early 1942, the unit murdered 6,280 Serbian Jewish women and children who had been prisoners at Semlin camp. Daily over two months, those women and children were taken from the camp and forced into a specially designed van, where they were gassed with carbon monoxide.

Serbia´s war crimes prosecutor has said he wants to try Egner in Serbia. The Simon Wiesenthal Center also has encouraged Serbia to try Egner and two other alleged Nazis here. ------ Associated Press Writer Dusan Stojanovic contributed to this report (© 2010 The Associated Press 12/21/10)