A Thai MP has apologised after stamping on a drunk tourist who groped a woman in a bar in Bangkok.

Move Forward Party MP Chorayuth Chaturapornprasit, 33, was drinking with his friends at a restaurant in the city's Ekamai area at around 2:30 am on August 11 when a stranger in a black shirt sidled up to the group.

The man was seen probing a woman's personal space before stumbling into her back, then grabbing her neck. Chorayuth, wearing a black waistcoat and white shir, asked the woman if she knew the man, to which she replied 'no'.

The MP then gently pushed away the man's arm to stop him but the tourist slapped him on the side of his head.

A shocked Chorayuth stood up, only to be shoved back by the bulky man, who slipped and fell on his bottom on the floor.

Several men, including the MP, then descended on the tourist and kicked him while he was down. Frantic restaurant staff tried to break up the fight.

Both parties reportedly left the restaurant without filing complaints with the police and the MP, the representative for Bangkok's Yannawa and Bang Kho districts, publicly apologised for the fracas.

In a statement on August 12, Chorayuth wrote: 'I acknowledge that my actions were wrong, and I should not have retaliated with violence. I assume complete responsibility for my actions and extend my sincere apologies to people who have trusted me as their elected representative. This incident is an important lesson to me.'

He also called out an establishment-supporting local news outlet for publishing an edited video of the brawl which did not show the start - in which he defended the woman and without interviewing him.

He said: 'I will not be giving further interviews because this will not benefit the people. I hope the media understands.

'Finally, I apologise to all of you for the incident that occurred. From now on, I will continue to strive to be fit for the House of Representatives.'