A blackmailer whose parcel bomb sparked the evacuation of a German Christmas market last week demanded 10 million euros ($11.8 million) worth of bitcoins, a news report said on Wednesday.
The German-language message demanding an untraceable payment in the virtual currency was addressed to the parcel delivery service DHL, Bild daily reported.
The bomb, containing explosive powder from Polish fireworks, nails and screws, was received by a pharmacy adjacent to the Christmas market last Friday.
Bild reported that it included a battery-powered trigger device, and that the package made a hissing sound when it was opened but failed to detonate.
Police, on high alert one year after a militant attack on a Berlin Christmas market killed 12 people, quickly cleared the festive market in the city of Potsdam near the capital.
Police are searching for one or more suspects in Berlin or its surrounding Brandenburg state, after a DHL parcel believed to have come from the same source caught fire last month when it was opened in another city in the same eastern region.
The blackmailers have threatened to send more parcels in the pre-Christmas season unless DHL pays, police warned last week, calling on Germans to remain vigilant.