Polish police have arrested eight people suspected of dealing "designer drugs" after more than 200 people were sickened by them in recent days.

The drugs consist of powerful psychoactive substances sold as powders or ground leaves with warnings that they not be ingested, language that has so far allowed them to be sold in a legal gray zone. Officials warn that their effects can be several times stronger than that of marijuana.

Since Thursday, more than 200 people have been hospitalized for poisoning by the drugs in and around the western city of Katowice.

Prime Minister Ewa Kopacz said Monday that her government plans to crack down on people producing and distributing the drugs, while health officials appealed to people not to use them.