Cardinal Reinhard Marx of Munich led a ceremony honoring the liberation of Dachau with foreign pilgrims, many of them Polish, in attendance. Around 40,000 Poles were held in the concentration camp just north of Munich in Bavaria. The camp, set up in 1933, provided a prototype for similar detention facilities - many of them on occupied territory, such as Poland - later built up by the Nazi regime.

"We thank God for the gift of reconciliation, which has greeted our peoples in the past decades," Marx told the congregation in Dachau.

The camp was liberated by US troops on April 29, 1945, just days before the German capitulation on May 8/9. President Barack Obama called the site "a lesson in the evolution of darkness, how unchecked intolerance and hatred spiral out of control."

"Our hearts are heavy remembrance of the more than 40,000 individuals from every walk of life who died, and the more than 200,000 who suffered at Dachau," Obama said, vowing to work to prevent such atrocities from ever recurring.

Stolen 'Arbeit macht frei' sign replaced

On the anniversary, Dachau also replaced a missing relic on Wednesday, even as it hoped for the original to one day be returned. The cynical sign on the camp's gate, reading "Arbeit macht frei" ("Work sets you free"), was stolen in October of last year.

"With this replica, we cannot recreate the conditions from October 2014. But we can at least give every visitor the impression of the original conditions," said Bavarian Culture Minister Ludwig Spaenle.

There's no trace, as yet, of the thieves - and no sure knowledge of whether the original artifact is still intact. Karl Freller, the director of the memorials foundation, conceded that police were struggling for leads.

"We strongly suspect that there is an extreme right background to this. But there's no evidence at all," Freller said.

The infamous message, also present at the Auschwitz concentration camp, was also stolen from that site in 2009 - with the far-right perpetrators quickly captured and the sign returned to the memorial site.

msh/bw (AFP, dpa)