Fifty-three young people were arrested and 21 of them them tested positive for illicit drugs following a raid on a noisy disco raft along the Kwai Noi River in Muang district.
Local officials led by district chief Noppadol Sukitpraneekit, defence volunteers and health officials boarded speedboats to raid the raft floating along the river in tambon Koh Samrong at around 9.30pm on Friday.
When the officials arrived, they found many young people drinking and dancing.
Most looked intoxicated. The officials ordered the raft staff to turn off the music and turn on the lights. They then ordered the skipper to bring the raft to the bank of the river for an inspection.
Provincial narcotics prevention and suppression officials, police and soldiers were called to the scene to assist with questioning and drug testing and ensure that none of the 53 people on board could flee.
A search turned up drug paraphernalia, bags with traces of ketamine and some marijuana found scattered around the raft.
The initial interrogation revealed that the group had rented the raft to hold a birthday party for a 33-year-old woman.
All 53 people were asked to undergo urine tests. Ten males and 12 females, all aged 18-22, initially tested positive for methamphetamine and ketamine.
They were taken to Phaholponpayuhasena Hospital for a second test, with 21 positive results and one negative.
They were handed over to Muang district police for further legal action.
The operator of the disco raft denied any knowledge that the group was planning to hold a birthday party or use illicit drugs on the craft.
District authorities plan to call the raft operator in for questioning again on Monday.