In a twilight bid for justice nearly 70 years on, chief investigator Kurt Schrimm said the former Auschwitz guards now aged up to 97 should face charges of accessory to murder.
"The cases will be handed over to the respective public prosecutors' offices," Schrimm said.
Schrimm's Central Office for the Investigation of National Socialist Crimes in the southwestern city of Ludwigsburg, set up in 1958, has recommended bringing criminal charges against more than 7,000 people but has no powers to prosecute suspects itself.
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Instead it sends case files to regional prosecutors who then decide whether to file charges against suspects, who must also be judged fit to stand trial by the courts.
Schrimm said he could not say how many of the suspects would actually be prosecuted in the end.
"It is possible that very few will remain" of the 30 potential defendants, he said.
Victims' representatives welcomed the announcement.
"These crimes against humanity must not remain unpunished," Ulrich Sander of the Association of Victims of the Nazi Regime told German news agency DPA.
And the Nazi-hunting Simon Wiesenthal Center said the announcement marked "an important milestone".
"At the same time, today's positive development underscores the failure to take such measures during the past five decades, a decision which allowed thousands of the worst hands-on killers to elude justice," said the director of its Jerusalem office, Efraim Zuroff.
In an "Operation Last Chance" campaign in several German cities in July, the Simon Wiesenthal Center hung posters seeking information on the last perpetrators of the Holocaust still at large.
The German investigative office said it had initially identified 49 former guards from the Auschwitz-Birkenau camp in what was then Nazi-occupied Poland who were still alive but nine of the elderly suspects had since died.
Thirty live in Germany and will now be subject to criminal investigation.
Another seven live abroad -- including one in Israel -- and the investigation against them in Ludwigsburg is still ongoing.
Two people could not be found, the office said, and one had already been under investigation in the southern city of Stuttgart.
More than 6,000 SS personnel served at Auschwitz, where about 1.1 million Jews, Roma and Sinti and members of other persecuted groups died in gas chambers or of forced labour, sickness and starvation.
For more than 60 years German courts only prosecuted Nazi war criminals if evidence showed they had personally committed atrocities, but since a 2011 landmark case all former camp guards can be tried.
In that year, a Munich court sentenced John Demjanjuk to five years in prison for complicity in the extermination of more than 28,000 Jews at the Sobibor camp, where he had served as a guard.
Thomas Walther, who led the investigation that led to Demjanjuk's prosecution, hailed the Ludwigsburg announcement.
"It is the first time since the 1960s that the German nation... is going to investigate such a large number of its citizens (for war crimes) and perhaps charge them," he told AFP.
"It shows that 50 years after the first Auschwitz trials, a large number of these people still live among us and many of them have led quiet lives these last 50 years without ever being investigated. That is a major, major mistake of the German justice system."
Schrimm said that while the latest investigation focused on Auschwitz, it had other Nazi camps including Majdanek in occupied Poland in its sights.
"The Central Office is also looking through the archives in Russia, Belarus and Brazil for further names of possible perpetrators," he said.
The announcement from Ludwigsburg came a day after the start of a trial in Germany of a 92-year-old former SS officer for the murder of a Dutch resistance fighter nearly 70 years ago.
Dutch-born Siert Bruins, who is a German national, faces a life sentence if found guilty.
Since the Nuremberg Trials in 1945-1946, around 106,000 German or foreign-born Nazi soldiers have been accused of war crimes.
About 13,000 have been found guilty and around half sentenced, according to the Ludwigsburg office.
