The raid took place at a building in Åby, near Norrköping. The party was being held by the Topside biker gang.
“There was a Hells Angels member at the party. He was wanted by police and will be taken back to jail,” said police spokeswoman Pia Theselius.
The terms of the man’s parole stipulated that he was not allowed to visit biker gang premises. He was taken to the nearest police station.
Police had earlier in the evening checked all cars coming to and from the building. Following the discovery of weapons including four knives, a knuckle duster, tear gas and an expandable baton, police were granted a warrant by the district prosecutor to raid the building.
All partygoers were expelled from the building and made to wait in a nearby restaurant. Police found amphetamines during the search. Five people are suspected of being under the influence of drugs, and three are suspected of driving under the influence of drugs.