BERLIN - German authorities investigating the delivery of a package containing powerful firecrackers, wires and nails to a pharmacy near a Christmas market in the city of Potsdam said on Sunday that it was criminal activity rather than "terrorism".

Karl-Heinz Schroeter, interior minister of the state of Brandenburg where Potsdam is located, told a news conference criminals were behind the package which they had used to try to extort millions of euros from logistics firm DHL, which had delivered the package.

Police said it was highly likely that the package could have exploded.

Staff at the pharmacy in Potsdam, just outside Berlin, called the police on Friday after they discovered the suspicious package. The Christmas market was evacuated and the package was made safe by a police robot.

Schroeter said the market itself most likely wasn't a target. As the person who sent the parcel was still at large, officials declined to say if they had any clues about the sender's identity.

The market was reopened on Saturday with an increased police presence.

DHL warned the public not to open packages if they did not recognize the sender's address or if the sender's address was suspicious.

"As we find ourselves approaching Christmas, which is not only a time of peace, but also a time when many presents are sent, such an act of extortion is reprehensible," Schroeter said. He said all efforts were being made to catch those who sent the package.

The parcel had contained materials to create a bomb, including about 100 nails, an unidentified powdered substance, and a metal cylinder. It also contained a blackmail letter encrypted in the form of a QR code, Brandenburg police chief Hans-Juergen Moerke said.

Moerke said that a QR code that can be read using a smartphone. The extortion letter addressed to DHL was found in the code.

Authorities said the people who sent the package most likely lived in Berlin or in the state of Brandenburg, which surrounds the German capital.

They did not say how much money they had demanded, but said they had told DHL they would send more packages that could kill or injure if DHL, owned by Deutsche Post, refused to pay up.

An online company in the town of Frankfurt an der Oder received a similar package at the beginning of last month.

Reuters - Xinhua - AP