A group of ancient copper items found at a construction site in June, including three pieces of jewelry and an ax, has turned out to be possibly of "national significance," the northern German city of Osnabrück said on Friday, August 19, Deutsche Welle reports.

It said a collection of this size and type had never been found in Germany before.

The artifacts, which are thought to date back to the end of the Neolithic Age between 2,500 BCE and 2,000 BCE, were reportedly found at a building site on the edge of the inner city by a volunteer worker from the city's archeology department.

Experts said the artifacts were made using techniques developed in the southeastern European region.

The city said the items needed restoration to reveal all the details of design and production methods, adding that tests would be carried out to establish whether the items were perhaps among the oldest metal products in Germany, if not Europe.

The city's mayor, Wolfgang Grieser, said he wants the city to have the rights to present the find and has already received approval from the relevant authority in Lower Saxony, the German state in which Osnabrück is located.