Nazi-hunters are to launch a renewed campaign to track down former death camp guards and others involved in the Holocaust before the last remaining perpetrators of Second World War crimes die.

From Tuesday, thousands of posters will go up in four German cities – Berlin, Hamburg, Frankfurt and Cologne – featuring an image of the entrance to the Auschwitz-Birkenau death camp, an appeal for information and the offer of a €25,000 reward.

The aim, says Efraim Zuroff, director of the Simon Wiesenthal Centre's Israel office, is to enlist the help of the German public in finding surviving overseers of the death camps and members of the Einsatzgruppen, the mobile death squads responsible for mass murders during of Jews and others.

"The police start with the crime and then determine who the perpetrator is," he said from his office in Jerusalem. "Since 98 per cent of the perpetrators of the crimes of the Holocaust are dead we can't work that way.

"We work on tips and information regarding people suspected of being Nazi war criminals. Given that our task is to identify where those people are, that makes us dependent on the public."

In the past, the German public has proved keen to cooperate with Nazi-hunters. Since 2005, the Simon Wiesenthal Centre has been passed the names of 660 suspected war criminals across Europe, many of them from Germany.

Of these, 106 have been passed to prosecuting authorities, including seven in Germany – though none of these has yet resulted on trial.

The campaign, named Operation Last Chance II, was given fresh impetus by the conviction in 2011 of the death camp guard John Demjanjuk.

The Wiesenthal Centre believes this verdict means that under German law evidence of someone's involvement in any overseer activity in extermination camps is sufficient to warrant a charge of complicity in murder.

In May this year, an alleged former guard at Auschwitz, Hans Lipschis, 93, was arrested in Aaalen in southern Germany, as part of continuing investigations by German authorities into 50 guards at the camp who are still alive and living in Germany. Mr Lipschis claims that he was only a cook.

However not every such attempt has been successful.

On the Wiesenthal Centre's list of "Most Wanted" Nazi war criminals is Gerhard Sommer, 92, a former SS officer suspected of being involved in the massacre of 560 Italian villagers. He was convicted in absentia by a court in Italy in 2005, but he continues to live in Hamburg, and German authorities have said there is insufficient evidence for charges against him.

Another on the list is Soeren Kam, who the Centre says served as an officer in the SS Viking Division and took part in the murder of a Danish anti-Nazi newspaper editor. Germany refused to extradite Mr Kam to Denmark after a court in Munich accepted his claim that he was acting in self-defence when the journalist Carl Henrik Clemmensen was killed.

Because an offence of manslaughter or accidental death expires under Germany's statute of limitations, that meant Mr Kam could not face prosecution.

When The Daily Telegraph tracked him down six years ago in the Bavarian town of Kempten im Allgäu, he declined to answer questions about his past.

Nazi-hunters say that within two or three years all of the Holocaust's surviving perpetrators will be dead. Dr Zuroff's aim is to ensure that as many as possible face justice before they die.

"Given the fact that time is running out, we hope that these cases will be expedited as quickly as possible," he said.

Funding for the campaign has come from small-scale, private donations. The Centre has attempted to raise money from German firms – but only three out of 86 companies Dr Zuroff approached responded positively.

"Frankly, I was very disappointed," he said. "Germany is very keen to focus on dialogue and tolerance education, far less on the issue of finding the last perpetrators and making them pay for their crimes.

"Most countries prefer not to focus on their own criminality. Justice over the years in Germany has been partial at best."