Police raided a bar in Thailand that was allegedly prostituting sex trafficked minors.

Officers raided the Monkey Toys Club in Chiang Mai province on April 24 after receiving a tipoff from US anti-trafficking nonprofit Operation Underground Railroad (OUR).

With local cops - who are often paid off to turn a blind eye - unable to affect the operation, high ranking police chiefs descended on the venue that was allegedly providing sex services.

Initial investigations found that the bar had more than 100 employees, with around 30 to 50 working each day. Customers would 259 baht (around 7.5 USD) for a drink with the girls before paying extra for sex.

There was a raised platform where employees danced, while a karaoke room was located in the basement.

Thailand's Internet Crimes Against Children (TICAC) task force and local police raided the alleged brothel and arrested owner Worasa, 53, manager Krirk, 40, and another manager Tawatchai, 23, on suspicions of sexually exploiting minors and illegal foreign workers. Their surnames were redacted by police.

The cops also allegedly found three underage workers and 15 illegal immigrants in the establishment.

Deputy National Police Chief Police General Surachate Hakparn said: 'The Royal Thai Police received information from the charity Operation Underground Railroad that there was a bar prostituting children under 18. Therefore, we sent TICAC officers and Chiang Mai police to inspect.'

The suspected involved have been remanded in custody while they are interrogated.

Surachate added: 'If the investigation reveals they are guilty, the suspects will face charges of employing minors for prostitution.'

The raid is the latest action from the police chiefs in Bangkok as they target widespread corruption and bars involved in the sex industry.

Last month, Flirt Bar in Pattaya which is run by a British ex-pat who started the Nightwish Group was raided and the British manager was arrested.

While earlier this year, a bar in Phuket selling children was raided followed by bars in Bangkok owned by the same company.