Norfolk police arrested three men at Sundown Festival between Friday September 3 and Sunday September 5.
Two men in their twenties were arrested on suspicion of possession of drugs, with intent to supply.
A man in his 40s was also arrested over the weekend on suspicion of assaulting a police officer.
Police say they are also investigating a number of other reports.
Despite the three arrests, Norfolk Police praised the majority of festival goers who enjoyed the event safely.
Chief Inspector Kris Barnard of Norfolk Constabulary said: "It was great to see so many people enjoying themselves, while also following guidance to keep themselves and others safe. Considering thousands of people attended the festival, it was only a very small proportion that chose to act in such a way where an arrest was necessary.”
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