A suspected Nazi war criminal who was due be extradited from Philadelphia to stand trial in Germany has died.

Johann Breyer, 87, was accused of being a "Death's Head Guard" at Auschwitz death camp, which was responsible for the deaths of more than one million Jewish people during World War II.

He was ordered to be extradited from the US to Germany to stand trial for mass murder. But his lawyer, Dennis Boyle, said he died during the night at Jefferson University while awaiting extradition.

Breyer has been suffering from ill health since his arrest in June. In recent years, he has also suffered from a heart condition and dementia.

Prosecutors in Germany obtained an arrest warrant for Breyer last year, alleging he was a perimeter guard at the infamous concentration camp between 1942 and 1945.

Breyer's lawyers argued he had no idea about what was going inside the death camp in Nazi-occupied Poland.