“The break-in was professionally planned and carried out: three as yet unidentified perpetrators used a drill to get to the vault from an adjoining room in the cellar of the building,” police said in a statement.

The heist, which struck the customs office in the western city of Duisburg, took place on Sunday November 1st.

Witnesses said they had heard drilling sounds at around 6:00 am. Three hours later, three men dressed in dark clothing and dark knit caps were seen walking in and out of the building to load objects into a white van with sliding doors.

They then drove off with the van.

Another witness noticed a man walking around the customs office before getting into a car and driving off in the same direction as the van.

Photographs of the man taken by the witness were published by police, who are offering a €100,000 reward for information leading to the arrest and/or conviction of the suspects.