This is the shocking moment a drunk foreigner attacked pump attendants at a fuel station in Thailand.

The burly man, believed to be around 50, drove into a PTT gas station in Udon Thani province and began throwing rubbish out of his SUV on May 21 morning.

When the employees tried to stop him, he reportedly became angry and bizarrelt claimed that he was a policeman.

He then refuelled at a pump before walking out of his car and attacking a pump attendant, Jirawat Sunthorn, 25, in a drunken rampage caught on CCTV.

The footage shows how the bald suspect of unknown nationality, seen wearing a black shirt, stomped over and slapped Jirawat across the face, with the force of the blow knocking the cap off the Thai man's head.

A cashier, Pranee Uttasiriwong, 38, tried to intervene but was also struck on the head by the out-of-control customer.

The foreigner was said to have cursed at the staff in both Thai and English before driving away - flashing a thumbs up at the crew filming him as he fled the scene.

Police Captain Ratnicha Chuchuay of the Mueang Udon Thani Police Station said police received a report at 1 pm on May 21.

He said: 'We brought the victims to Udon Thani Hospital for a health check for documentation. 

'Witnesses will be summoned to provide testimonies to help us locate the suspect.'

The pump attendant Jirawat suffered a swollen right cheek and a bruised arm following the attack.

He said he had asked Pranee to talk to the foreigner to stop him from littering on the premises, but the man responded by insulting and attacking them.

He said: 'I have only been working at the gas station for just over a month, but I have never encountered anything like this before, even at my previous jobs. I want the man to be punished to the full extent of the law.'

Another employee, Sirikarn Parawong, 45, said she has been working at the fuel station for seven months and was shocked by the foreigner's behaviour.

She said: 'I have seen foreigners assaulting Thai people on the news, even though they live in our country. Working as a gas station attendant is a job with dignity, just like any other person, and it's an honest profession because they don't beg from anyone. This shouldn't have happened.'

The staff believe the man may have been staying in Thailand for a long time as he was fluent in the local language, and had even picked up the local accent in the region.

Efforts were underway to identify and track down the suspect.