Amsterdam police have set up more signs warning tourists of a potentially fatal narcotic being passed off as cocaine following the deaths of two British men after taking the drug.

The two Britons, aged 20 and 21, were found dead in a hotel room in the Dutch city yesterday, probably after using white heroine which had been sold as cocaine, police said.

“We found drugs in the hotel room and immediately had it tested to see if the composition was the same as other investigations into deaths and people getting sick, and that proved to be the case,” Rob van der Veen, a spokesman for Amsterdam police, said today in a telephone interview.

Police are using electronic signboards in tourist areas of Amsterdam to flash the message, in English, that “extremely dangerous cocaine is sold to tourists.” An additional sign was placed at Amsterdam Central station yesterday.

Seventeen people, mostly British, became unwell after using white heroine which they thought was cocaine, police said. Three men died while a “substantial number” had to be resuscitated. The police are investigating the matter.

“We assume that it’s only one person who’s selling this,” Van der Veen said. White heroine is more expensive than cocaine, so police are working on the assumption that the dealer doesn’t know exactly what he’s selling.

To contact the reporter on this story: Corina Ruhe in Amsterdam at cruhe@bloomberg.net To contact the editors responsible for this story: Fergal O’Brien at fobrien@bloomberg.net Alan Crawford, Eddie Buckle.

Photo Credit: Tourists walk down a street in Amsterdam. Funky Tee / Flickr