Prapakorn Waharak, 20, who works in the family jet-ski business at Naka island, off Phuket, lodged a statement with officials at the Damrungtam ombudsman's office at Phuket Provincial Hall in Phuket City.
Khun Prapakorn said he and two other youths were tested for drugs on August 22. He failed the test and police said they found 2.4 grams of ya ice amphetamine in his possession.
Khun Prapakorn alleges that after freeing the other two youths who tested negative, five plain clothes officers from Thalang beat him in a police box.
He said he was examined by doctors at Thalang Hospital and later at Vachira Phuket Hospital in Phuket City.
Freed on bail on the drug charge, he later tried to complain without success at Thalang Police Station.
Today, five days after the alleged assault, Khun Prapakorn was able to show few signs of the beating except for scars where handcuffs cut his wrists.
Khun Prapakorn and an uncle supplied the names of the five officers to Damruntam officials today.
At Thalang Police Station, Colonel Witon Kongsudjai said he was new at the posting and would need to consult with colleagues before commenting on the case.
Jet-skis were declared legal at Naka Island earlier this year by a Phuket official.