AN ELDERLY NAZI war-crimes suspect will remain jailed in Philadelphia as part of a German criminal case after a U.S. judge denied him bail this week.

Defense lawyers argued that Johann "Hans" Breyer, 89, is in frail health and deteriorating in prison. He has heart disease and dementia, and he had a stroke in recent years.

"Due to Mr. Breyer's age and condition, he is incapable of fleeing or endangering others, as he himself needs daily assistance," lawyer Dennis Boyle said in a bail petition filed after his arrest last month.

German authorities hope to try Breyer on accessory-to-murder charges for his guard service at the Auschwitz death camp in 1944. Breyer told the Associated Press in 2012 that he was forced to work there as an SS guard but never took part in the mass killing of Jews and others.

He was charged last month with 158 counts of accessory to murder - one for each trainload of victims brought to Auschwitz during his time there.

U.S. Magistrate Timothy Rice on Tuesday denied Breyer's bail request without commenting. Assistant U.S. Attorney Andrea Foulkes had opposed bail, suggesting that Breyer instead try to move up his extradition hearing, or waive his appearance, as he might then be moved to a prison with more advanced medical care.

Breyer, a retired toolmaker, has lived in Philadelphia since 1952. He survived earlier U.S. efforts to be stripped of his naturalized American citizenship over his Nazi ties when a judge found he had joined the SS a few months before his 18th birthday.

Breyer will remain at a federal prison in Philadelphia until an extradition hearing scheduled for Aug. 21. German authorities hope to try him on the criminal charges in Weiden, Bavaria.

However, defense lawyers could ask the State Department to block the extradition on humanitarian grounds, if it is approved.