Germany has arrested three suspected former SS guards of the Nazi death camp Auschwitz in a series of home raids across three states.

The three men remanded in custody are aged 88, 92 and 94 and live in the southwestern state of Baden-Wurttemberg, said prosecutors in the city of Stuttgart.

They are suspected of having participated in murders at the Nazis' Auschwitz extermination camp in occupied Poland where more than one million people were killed in World War II.

The three elderly men underwent medical tests and then faced a judge who confirmed their fitness to be detained in a prison hospital, prosecutors said in a statement.

Further home raids were carried out at three more locations in the state, as well as at other homes in the western states of Hesse and North Rhine-Westphalia.

"Various records and documents from the Nazi era were seized, and their evaluation is ongoing," prosecutors said.

Frankfurt prosecutors separately confirmed two raids in Hesse state on Wednesday, in which police searched the homes of two men, aged 89 and 92, but reported no arrests.

The men were suspected of having served as Auschwitz SS guards from 1942 to 1944.

The German office investigating Nazi war crimes last year sent files on 30 former Auschwitz personnel to state prosecutors with a recommendation to bring charges against them.

The renewed drive to bring to justice the last surviving perpetrators of the Holocaust follows a 2011 landmark court ruling.

For more than 60 years German courts had only prosecuted Nazi war criminals if evidence showed they had personally committed atrocities.

But in 2011 a Munich court sentenced John Demjanjuk to five years in prison for complicity in the extermination of Jews at the Sobibor camp, where he had served as a guard, establishing that all former camp guards can be tried.

More than one million people, mostly European Jews, died at Auschwitz-Birkenau, operated by the Nazis from 1940 until it was liberated by Russian forces on 27 January 1945.