Dutch police have discovered an illegal cannabis nursery hidden in a World War II bunker, a spokesman said on Sunday.

“Police on Friday discovered the illegal cannabis nursery in an old bunker after being tipped off by outdoor enthusiasts,” Cor Spruijt told AFP.

The group was hiking near the North Sea at Katwijk, north of The Hague, when they discovered the hidden hot-house.

Police found 168 cannabis plants, most of them at least one metre (more than three feet) high, as well as equipment and an electricity supply illegally tapped from a nearby water pumping station, Spruijt said.

The plants were taken away and destroyed, Spruijt said.

Although cannabis is technically illegal in the Netherlands, the country in 1976 decriminalised possession of small amounts and it is widely available.

However, growing and selling any quantity over five grammes is illegal, meaning the cultivation and sale of large amounts of cannabis is largely in the hands of organised crime.

The old bunker forms part of the so-called “Atlantikwall”, constructed by the Nazis from 1942 to protect the North Sea and Atlantic coastlines from Allied invasion.