Three Danish tourists were hospitalised in Amsterdam on Wednesday night after taking white heroin which they had been sold as cocaine, the city council said on Friday.

The three, aged 21 to 24, are the first victims to be recorded since November 25, when the city council began a major information offensive. Three British tourists died after taking the drug and at least 14 were taken ill during the first wave last year.

The campaign warning tourists not to buy from street dealers will now be restarted, the council said.

‘Preventing more people becoming victims is more important than… any eventual negative effect on the city’s image,’ the council said.

It is not yet clear if the drugs involved in this latest case come from the same source as last year. The public prosecution department has issued a €15,000 reward for a tip leading to the dealer being tracked down.