Seven teenage thugs suffered instant karma for picking a fight with a group of hardened Muay Thai fighters.

The violent drunks allegedly charged at the athletes unprovoked, sparking a brawl at the Khlong Mae Kha Bridge in Chiang Mai, northern Thailand, at around 1 am on May 7.

Footage shows a delinquent with dyed hair swaggering onto the scene before rushing to punch one of the Muay Thai fighters drinking beer.

However, the yobs soon found themselves out of their depth as the three kickboxing experts retaliated, trouncing them despite their superior numbers.

Prawit Petboribundee, 34, a trainer at the Wildcat Muay Thai boxing gym, said: 'On that day, I brought my Muay Thai athletes to watch a boxing match at the Kalare Night Bazaar. Then, my junior called me and asked me to join him for food and drinks at the Khlong Mae Kha Bridge. 

'While we were chatting, I noticed a group of seven teenagers approaching from a distance. They looked like trouble so I asked my junior to take a video in case anything happened.

'As expected, they immediately threw punches at us. I was unsure of what to do at first, but I intervened when I saw my junior being attacked.

'It turned into a chaotic brawl, but they were no match for the three of us, who are trained in Muay Thai. The attackers eventually apologised with a wai gesture, but I delivered kneed them and scolded them for assaulting strangers for no reason.'

Prawit went to the hospital for a broken finger on his right hand, cuts from a metal sign on his left hand, and a small wound on his back.

He urged authorities to investigate the issue, which he said could tarnish Chiang Mai's reputation as a tourist destination, adding not everyone was fortunate to know self-defense.

Meanwhile, a Muay Thai fighter named Placarp, 19, said he was confused when the thugs attacked them all of a sudden.

He said: 'It was my first time being involved in a brawl. I was lucky my coach was there to help defend us.'

Residents said brawls between teenage gangs were a perennial problem in the area, but they were too afraid to intervene themselves.

They called on authorities to patrol the streets at night when the fights usually occur.

Police said they have studied the surveillance footage and are still trying to trace the alleged attackers.