A sniffer dog is being used by the Polish police in their search for thieves who took the Arbeit Macht Frei (work sets you free) sign over the entrance to Auschwitz, the former Nazi camp. (photo, from bbc.co.uk)
A replica of the sign has temporarily been put up for the tourists who visit the site where more than one million people, mostly Jewish, were murdered.
The theft took place on Friday and has caused outrage in Israel, Poland and elsewhere.
“The theft of such a symbolic object is an attack on the memory of the Holocaust, and an escalation from those elements that would like to return us to darker days,” said Avner Shalev from the Yad Vashem memorial centre in Jerusalem.
“I call on all enlightened forces in the world who fight against anti-Semitism, racism, xenophobia and the hatred of the other to join together to combat these trends.”
In Brussels, European Parliament President Jerzy Buzek, a former Polish prime minister, appealed to the thieves to return the sign.
“Give it back out of respect for the suffering of over a million victims, murdered in this Nazi camp, the biggest cemetery of humankind,” he said.
A police spokeswoman said the wrought-iron sign was half-unscrewed, half-torn off from above the death camp’s gate between 03:30 and 05:00 on Friday.
Stealing the 5 m (16 ft), 40 kg (90 lb) sign would have requested at least two people, said investigators.
Police said they were reviewing footage from a surveillance camera that overlooks the entrance gate and the road beyond but declined to say whether the crime was recorded, The Associated Press news agency reports.
It might have been too dark for the camera to have captured images, said Auschwitz museum spokesman Jaroslaw Mensfelt.
He added that the thieves apparently carried the sign 300m (yards) to an opening in a concrete wall. The opening was left intentionally to preserve a poplar tree dating back to the time of World War II.
Four metal bars that had blocked the opening had been cut and footprints in the snow led from the wall opening to the nearby road, where police presume the sign was loaded on to a vehicle.
Earlier, another police official said that while all leads were being considered, police were focusing on a theft ordered by a private collector or a group of individuals.
It is the first time the sign, made by Polish prisoners, has been stolen since it was erected in 1940.
A 5,000-zloty ($1,700) reward has been offered for information leading to the capture of the thieves.
Since 1947, Auschwitz, which receives more than a million visitors a year, has been run as a state museum.
In order to help preserve the camp, Germany recently pledged 60m euros to an endowment fund.