This is the shocking moment a tourist knocked out a transgender sex worker who was pestering them in Thailand.

CCTV footage shows two foreigners being approached by the Thai 'ladyboy' in a yellow dress while they were walking along the Walking Street red-light district in Pattaya on June 17.

The woman was seen pointing at one of the men in a white shirt, who then delivered a knockout punch that left her sprawled on the pavement.

Onlooker Ton, 37, said: 'The tourists were fighting with the transgender woman. I don't know what they were arguing about, but one of them suddenly punched her before they both ran away. The ladyboy's friends called officers to give her first aid.'

The Pattaya Police Station said no reports regarding the incident have been filed.

A police spokesman said: 'If the victim wants to take legal action against the other party, she can lodge a complaint with the police immediately.'

Hell-raising coastal city Pattaya emerged as a nightlife destination in the 1960s when Thailand fought alongside the United States. The Southeast Asian outpost provided them with land for eight military bases, aiding the massacre of North Vietnam and the deaths of two million civilians in the 1950s and 1960s.

In between killing missions, American GIs would have debauched ‘rest and relaxation' leave in the coastal enclave, leading to a raucous nightlife industry that has endured to this day.