Police at Amsterdam's Schiphol airport on Thursday released a warning for hallucinogenic dark chocolate bars after a homeless man ate one and confused their uniforms with wedding dresses.

"He ate some and we found him hallucinating", mixing up police uniforms with wedding dresses, police spokesperson Rob Stenacker said.

"Several days later he brought us another bar that he had just found and we passed it on to the forensic institute" of The Netherlands, he said.

Tests showed the 72% cocoa dark chocolate contained psilocine, a mind-altering substance found in hallucinogenic mushrooms and considered to be a hard drug.

Police later found more chocolate bars on the ground and in airport dustbins.

"They were very likely bought in The Netherlands and abandoned at the airport by travellers who didn't dare to take them on board [the plane]," Stenacker said.

Police warned the public to be careful if they found any abandoned dark chocolate: "Don't eat it, you don't know what's in it. Imagine what would happen if a child ate it."

The sale of hallucinogenic mushrooms is tolerated in The Netherlands in so-called "smartshops" but it is forbidden to turn them into other food products. -- AFP