A banned substance which has been linked to deaths in Europe is in circulation in Derbyshire, police have revealed.
In March, police seized a packet of a suspected legal high called Black Mamba in Derby city centre.
Tests revealed the substance actually contained a banned compound called MDMB-CHMICA.
The substance was linked to two deaths and three hospitalisations in Germany last year.
Police in Derbyshire are again urging people not to take legal highs – because it is not known what they actually contain.
Steve Holme, a drugs expert at Derbyshire Constabulary, said: “This substance was found in Derby city centre but it will be circulating in towns across the entire county, including Chesterfield.
“It’s a very worrying situation.
“Our advice is simple – do not take legal highs.
“When you buy any of these products you are taking a massive gamble with your health.
“You can never know exactly what is in them and you do not know whether the contents are safe to take.
“It’s so important to get that message across – we don’t want anyone to die because of these substances.”
Chesterfield is well-known for its problem with legal highs.
A special investigation by the Derbyshire Times last summer revealed how shopkeepers feared parts of the town centre had become ‘no-go’ zones because of yobbish behaviour fuelled by the substances.
Police said the majority of legal highs had been bought from the controversial Reefer shop in Knifesmithgate.
The store now has a new identity and is no longer selling the substances.
Meanwhile, police have stepped up patrols around the Crooked Spire church amid a number of reports about suspected use of legal highs.