A Swedish tourist was allegedly attacked and robbed by three thugs when he intervened to protect a waitress who was being harassed.

Roy Torbjorn, 55, was drinking at a karaoke bar when he noticed the rowdy locals insulting the woman and asked them to stop in Chiang Mai, Thailand on April 8.

Shocking CCTV footage shows how a Thai men leapt over the counter and repeatedly punched terrified Roy in the head. Several others then joined in the sustained attack.

Several bystanders joined in to try and separate the attackers before the bar maid began firing a water hose from the sink at them. The men then fled on notorcycles with Roy's gold chain worth around 1,800 Euros which they allegedly ripped from his neck during the fracas.

Roy's girlfriend reported the incident to the San Kamphaeng Police Station and the three alleged attackers were arrested.

Roy said: 'I was celebrating my birthday with relatives. Then I saw a waitress being harassed and pulled into the bathroom, so he intervened and tried to stop the attackers.

'I noticed after that my gold chain with a Buddha image on it was missing.'

Roy's wife Duangporn Sokram, 44, said that she and her husband travelled back from Sweden to visit her family in Thailand on March 28.

She held a birthday party for her husband and brother on April 7 at their house, which continued at the karaoke venue with a total of seven people.

When the Swedish man went to use the restroom, he allegedly witnessed a waitress being assaulted in the women's bathroom. He then attempted to intervene and help her.

Duangporn said that after helping the waitress and returning to his seat, the group of three men insulted him in the Thai language but as he did not understand Thai, he did not respond to them.

When the Swedish man and his group tried to leave, the group of men unexpectedly attacked him by kicking, punching, and pressing him down on the table. His relatives tried to intervene and stop the attack.

During the scuffle, Duangporn said she was bitten on her right arm by the thugs, while her husband sustained cuts and bruises all over his body.

She said: 'I'm very shocked and sad about what happened. I am relieved that the attackers have been arrested.

'It's important to protect Thailand's tourism image. As well as the police prosecution, I will take legal action against the attackers myself.'

The waitress, 29, told police she had only recently started working at the bar but on that night she 'was too drunk to serve the customers properly'.

She said: 'When one of the men tried to pull me into the toilet, I resisted and used my foot to push the door closed.

'I was fortunate that I was helped by the Swedish man. They had been harassing me and trying to ask for my phone number.'

Police Colonel Nattapon Chanmano, superintendent of San Kamphaeng Police Station, reviewed the CCTV footage and was able to apprehend three suspects. They were named as Daeng Lungsaeng, 25, Aeng Kam, 25, and Sa Ong, 22, from nearby homes.

The three suspects were arrested at a construction site in a nearby village, and they later confessed to assaulting the Swedish tourist and harassing the waitress. However, they denied stealing the necklace.

Police said all three were charged with assault and theft.