WARNING Please note, we have found blue punishers in the confiscation box. They are potentially lethal. This is what we have been warning about #BeSafe pic.twitter.com/iyMCRQtg3l— Parkalife (@Parklifefest) June 9, 2018 Dangerous drugs which are mis-sold as MDMA but cause psychosis and keep young users awake for up to three days are being sold at Parklife festival, narcotics experts have warned.”Fake MDMA” drug N-Ethyl-Pentylone, which is three times as strong as the drug it mimics, has been found at the Manchester music festival.It was first detected in the US in 2016, and then it spread to Australia in 2017, where users had to be sedated after the effects of the narcotic substance took hold. It has also been linked to deaths and mass casualties at music festivals around the world.The drug is so dangerous because it can be easily mistaken for MDMA, drug testers from The Loop said.However, it does not give the same high as MDMA, which leads some to accidentally overdose, and it is three times as strong.Although users feel a short, semi-euphoric high when they first ingest the drug, this gives way to three days of sleepless nights, paranoia and psychosis. We tested a gram of n-ethyl pentylone @Parklifefest yesterday – looks & smells same as MDMA crystal. Relieved this user didn’t take it. Take care & seek medical attention if unwell. #JustSayKnow #TimeToTest pic.twitter.com/mWVkPHvhPQ— The Loop (@WeAreTheLoopUK) June 10, 2018 The popular dance festival was cancelled as a “safety precaution” after the death of 18-year-old care worker Georgia Jones and Tommy Cowan, a 20-year-old man.Before their deaths, organisers said they were aware of “dangerous high strength or bad batch” of drugs on site.The Loop also found the dangerous super-strong pills on site at Mutiny.Parklife alluded to this, tweeting: “We all saw the sad news last weekend. There are batches of very bad pills out there at the moment. Please act responsibly and look after each other.”A spokeswoman for Greater Manchester Police confirmed 28 people had been arrested at the Heaton Park festival on Saturday, 23 of them on suspicion of committing drugs crimes. Parklife Festival organisers warned attendees to take special care after super-strong ecstasy tablets were found in confiscation boxes.They wrote: “WARNING Please note, we have found blue punishers in the confiscation box. They are potentially lethal. This is what we have been warning about.”The same “bad pills” were linked to two deaths and 12 hospitalisations at Mutiny festival in Portsmouth two weeks ago. The Loop found a gram of the substance at Parklife festival, leading to worries that more was in circulation, being mis-sold as MDMA.When the drug hit Australia in 2017, Dr David Caldicott, an expert in emergency medicine, told The New Daily: “It has been clearly responsible for the deaths of people overseas, and a rather unfortunate phenomenon known as ‘mass casualty overdoses’, where 10-20 people drop simultaneously. So, it’s of great concern to the music festival environment.” Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings.