Dutch police have discovered an illegal marijuana plantation in a World War II bunker near the coastal town of Katwijk, news agency AFP says on Monday.

Police found the plantation on Friday after they were tipped off by walkers.

The bunker contained 168 plants and was powered by electricity illegally tapped from a nearby water pumping station, spokesman Cor Spruijt told the news agency.

The Dutch dune area is riddled with bunkers and military defences, constructed by the Nazis as part of the Atlantic Wall.

Cannabis consumption is technically illegal in the Netherlands but police turn a blind eye to the possession of up to five grammes for personal use.

Up to 95% of the marijuana grown in the Netherlands is exported or consumed by foreign tourists, according to justice ministry research published at the end of last year.