Selangor police chief Hussein Omar Khan said the suspects, aged between 20 and 30, were apprehended in Selangor between Jan 8 and 12, Berita Harian reported.

“The three were selling drugs separately. One of them was present there at the concert,” he was quoted as saying.

Hussein also said a total of seven people, including the four who died, were found to have ecstasy in their systems.

“The pills were sourced both externally and within the concert venue,” he said.

Hussein said police and the local authorities will not prohibit concerts in the future, but will tighten regulations.

The regulations will include stricter controls over music genres, audience capacity, venue size and the organisers’ readiness to handle emergencies, including deploying first aid teams.

Police previously said the four who died after attending the event at Sunway Lagoon on Dec 31 were suspected to have taken ecstasy.

Their deaths had prompted authorities to suspend concert permits in Selangor, with the state government saying it would review concert guidelines.