Polish police have questioned two Canadian teachers who allegedly stole parts from the Auschwitz-Birkenau train tracks.
The pair, both said to be men in their 20s, were detained after security guards found them in possession of spikes from the railway which carried Jews and other Nazi victims to the concentration camp.
They have been released and police have not said whether they will face charges. A Polish radio station reported that the men were looking for a memento of their visit.
Bartosz Bartyzel, a spokesperson for the Auschwitz museum, said guards handed the men over to the police.
He said: "The men were caught red-handed by security.
“For us, this is a case of desecration of a place of memorial. These items are priceless.”
Around 1.1 million people were killed at Auschwitz as the Nazis sought to exterminate all European Jewry in their Final Solution.
The incident comes just weeks after survivors commemorated 70 years since the first rail convoy was sent to Auschwitz.
In 2009 the cast iron sign reading "Arbeit Macht Frei" at the entrance of the Auschwitz concentration camp was stolen and vandalised.