Four immigration officials at a busy Bangkok airport have been demoted after a probe found they were taking bribes from Chinese tourists to fast-track their visa applications, an official said Tuesday.
The Chinese make up about a quarter of Thailand's 35 million tourist arrivals a year, making them the kingdom's largest visiting bloc by nationality.
They usually wait in long lines at busy immigration booths at Don Mueang -- one of the two international airports in Bangkok -- where they pay 2,000 baht (about $60) for visas upon arrival.
But Major-General Surachate Hakparn, the newly installed chief of the immigration bureau, told AFP he was tipped off on how some are able to jump the queue.
"We recieved the allegations from tourists that they can fast-track their application services if they pay a 300 baht 'tip' at the (so-called) fast lanes," Surachate said.
This prompted an investigation, which led to an official "admitting" to receiving the fees.
"He, along with three senior immigration officials including a superintendent, were demoted while the investigation is ongoing," he said.
Promoted last month to immigration bureau head, Surachate -- who was formerly deputy tourist police chief -- has shaken up the new position by enacting some immediate visible changes.
Last week, massive signs were erected in airports nationwide, reading in three languages that no tips were required to get through immigration.
"I've heard about this happening for a long time," Surachate told AFP. "And now we are serious to get rid of it."
The removal of the four immigration officials follows a row last month when a video clip of a Chinese tourist being hit by an airport guard surfaced.
Two senior airport employees were suspended because of it.
The brawl prompted a flurry of reactions from the highest levels of government, with a spokesman saying that junta leader Prime Minister Prayut Chan-O-Cha was "upset" by the incident.
The prompt reaction highlights how valuable the lion's share of tourists from China is to Thailand, as their numbers have been steadily dropping since a July boating disaster in Phuket left dozens dead.
The Ministry of Tourism and Sports has estimated that it would lose more than half a million Chinese tourists angered and scared over the boat tragedy.