It was found in a bin, within walking distance of the stadium where the European Athletics Championships took place until Sunday. Officers say there were things like syringes, needles, and catheters inside.
Meanwhile former world high jump record holder Patrik Sjöberg told the media he had been detained by the police after taking cocaine at a party in Gothenburg.
Former national 400 metres hudler Sven Nylander said he had also been held by police on suspicion of drugs offences. He is a campaigner against doping in sport.