Polish prosecutors are investigating if workers have violated laws protecting buried human remains when they apparently dug up bones at the site of a former Nazi concentration camp and a Jewish cemetery.

Police say they found bones at the site of the World War II Plaszow concentration camp after a company did gas pipeline maintenance work there. Krakow police spokesman Mariusz Ciarka said Tuesday the bones have been sent for forensic examination to determine if they are human.

Police were alerted to the site by a local Jewish community leader, who had been notified about the digging by an anonymous caller.

The Nazis set up the camp on the site of the Plaszow Jewish cemetery during the war. Today it is only marked by a stone memorial.