Operation Last Chance: The final attempt to track down ageing Nazi war criminals before they die The Simon Wiesenthal Center launches poster campaign in German cities Only two of the center's top ten most wanted list are under the age of 90 Campaign follows claims that up to 50 Auschwitz guards could be alive The hunt for the last remaining Nazi war criminals follows the 2011 conviction of John Demjanjuk, a former guard at the Sobibor camp who died last year Nazi hunters are to hang posters in major German cities and offer rewards of £20,000 in a bid to bring the last war criminals of the Third Reich to justice. The Simon Wiesenthal Center believes members of the public may have vital information to help with the last round-ups to ensure murderers do not die peacefully in their beds. The posters feature a photo of the entrance to the Auschwitz-Birkenau concentration camp, where 1.3million people are thought to have died, and the slogan, 'Late. But not too late! Operation Last Chance II. They will appear in the cities of Berlin, Hamburg and Cologne from Tuesday and will display a hotline number for people to call. Germany is being targeted following claims that up to 50 Auschwitz guards may still be alive. One, Hans Lipschis, was charged in May on suspicion of participating in murder and genocide after being arrested in Stuttgart. Operation Last Chance II was launched in December 2011 to help step up prosecutions following the conviction of John Demjanjuk in Munich following decades where only the top officers were prosecuted. An Ukrainian-born S.S. man, the retired car-plant worker from Ohio was deported to Germany and convicted in May 2011 of 28,060 counts of being an accessory to murder at the extermination camp of Sobibor in Nazi-occupied Poland. They will displayed in German cities from Tuesday The poster for Operation Last Chance II features the gates to Auschwitz-Birkenau, the camp where 1.3million people are thought to have died He attended the 18-month court proceedings in Munich - birthplace of Adolf Hitler's Nazi movement - in a wheelchair and sometimes lying down. Demjunjak denied the charges and was sentenced to five years in prison but was freed because of his age and died in a nursing home last year. The Wiesenthal Center's top ten most wanted list has only two suspects under the age of 90. 'Every single prosecution is an important reminder that justice can still be achieved for the victims of the Holocaust,' said Efraim Zuroff, director of the Wiesenthal Center's Jerusalem office. Efraim Zuroff of the Simon Wiesenthal Center, which is launching a final campaign to bring Nazis to justice for their parts in the Holocaust Alleged Hungarian war criminal Laszlo Csatary, 98, denies that he was involved in the murder of 15,700 Jews by helping to deport them to Auschwitz This also is an important contribution against forgetfulness of future generations. The advanced age of the perpetrators should not be a reason to discontinue prosecution, since the passage of time in no way diminishes their guilt, and old age should not protect murderers. Mr Zuroff told the Times: 'Justice at this stage does not make a pretty sight. These people are very elderly. But what I tell the people is, do not think of some old frail person, think of someone who, at the height of his physical powers, used all his energy to kill innocent men, women and children. We are talking about people involved in mass murder, day in, day out, so it is important to prosecute. Last month 98-year-old Laszlo Csatary was arrested in Hungary for helping to deport Jews to Auschwitz. Prosecutors say Laszlo Csatary was the chief of an internment camp at a brick factory in Kosice - a Slovak city then part of Hungary - in May 1944. He is alleged to have overseen the deportation of 15,700 Jewish detainees to concentration camps. The pensioner is also accused of beating them with his bare hands and a dog whip. He also allegedly refused to allow ventilation holes to be cut into the walls of a railcar crammed with 80 Jews being deported. Hans Lipschis is among the 50 Auschwitz personnel thought to still be alive in Germany today who are now being investigated following the Demjanjuk conviction. Lipschis admits he served with the SS at Auschwitz but claims he was only a cook. He was deported from the U.S. in 1983 for lying about his Nazi past when he immigrated to Chicago in the 1950s.