Anti-terrorist police in eastern Germany may be forced to return more than 2,000 assault rifles after their manufacturer lost a legal patent row with a rival.

Judges have ruled that the water-repellent technology in the C. G. Haenel-made weapons had been ripped off from Heckler and Koch’s MP5 submachine gun.

Now anyone who owns one of the CR223 guns is expected to send them back to the maker, where it will be destroyed.

Police in Saxony had taken delivery of 2,200 of the now-banned weapons to arm their anti-terror units.

The verdict – delivered at the Higher Regional Court in Dusseldorf after a two-year legal battle – could cost them up to GBP 8 million.

Ironically, Saxony’s special police forces were previously equipped with Hecker & Koch’s MP5 model.

Back then, the interior ministry argued the acquisition of the 2,300 semi-automatic rifles was necessary to ensure the safety of citizens in times of increasing terrorist threats.

Twenty-five people were detained last month when police raided homes across Germany to foil an alleged plot of far-right Reichsburger conspiracy theorists.

Two of the arrests occurred in Saxony.

A spokeswoman for the ministry said today (5th January): “We will discuss the judgement before drawing any conclusions. There will be talks with the manufacturer.”

Dr Eike Nielsen is a spokesman for the Federal Patent Court.

He told the Bild newspaper: “It’s up to the police in Saxony whether the weapons will be handed back. The police hasn’t breached patent laws, it hasn’t been involved in the legal wrangles either.”

Saxon Police President Joerg Kubiessa emphasised: “Our police forces remain fully operational. We now have to carefully evaluate the possible consequences.”

The verdict is not yet legally binding. Neither of the involved weapons manufacturers gave a statement.