A thousand shops that used legal loopholes to sell designer drugs have been closed, Polish authorities said and also kicked off a campaign against the trendy synthetic narcotics.
"The state will not flinch when it comes to using all legal means available in the struggle against these substances," Justice Minister Krzysztof Kwiatkowski told reporters.
In a nationwide operation over recent days, police and health inspectors placed seals on the doors of shops selling laboratory-created drugs, which imitate the effect of banned narcotics but whose individual chemical components are not necessarily illegal.
Kwiatkowski said the government would bring in amendments to existing legislation in a drive to plug the loopholes.
They would include a three-year prison sentence for anyone who supplies minors with a substance posing a risk to their health or life, he said.
Such drugs have made growing headlines over recent weeks, with several users ending up in hospital. There have been a handful of fatalities believed to be linked to their consumption.
"This is going to be a long and difficult fight because our opponent is extremely well-prepared, rich and determined," said Kwiatkowski.
The authorities have had trouble clamping down because the drugs' makers have kept one step ahead, varying the composition -- as soon as one chemical component is banned, they replaced it with another that has a similar effect.
In addition, sales outlets have used ruses to duck inspections, such as labelling packets of drugs as collector's items or garden fertiliser, or marking them unfit for consumption.
Another amendment planned by the government includes allowing health inspectors to pull from the market any substance suspected of being harmful, for at least to 18 months while tests are carried out.
The owner of a chain of shops selling the chemical highs told the Polska newspaper he planned to take legal action over the state shutdown.