The robbers who staged an elaborate heist in Kozani, northwestern Greece, over the weekend and drove away with a 2-ton safe were likely disappointed to discover that it only contained official papers, police said yesterday. The thieves broke into a municipal transport office and tried to open the safe, the chief of police in Kozani, Constantinos Voutsidis, said. «They could not open it so they took it with them,» he added. A truck fitted with a crane was used to hoist the safe away but there were only 1,800 blank driving licenses and no cash inside, authorities said. Police have been informed of the serial numbers of the stolen licenses. The thieves also stole some electrical and precision equipment from a surveyor’s office in the same building.