National police chief Pol Gen Damrongsak Kittiprapas has admitted the practice of highway police demanding and taking bribes from truck operators has long been in existence.
It had "exploded" into public awareness recently only after details were posted on social media, Pol Gen Damrongsak said on Wednesday.
He was speaking after Pol Lt Gen Jirabhop Bhuridej, the Central Investigation Bureau (CIB) chief, signed an order reassigning Highway Police commander Pol Maj Gen Ekarat Limsangkas to the CIB operations centre.
The move followed reports on social media that drivers of overloaded lorries were not being arrested at highway weighbridges if they had one of several stickers on their vehicles showing bribes had been paid.
Pol Maj Gen Jaroonkiat Pankaew, commander of the Anti-Corruption Division, was assigned to concurrently act as commander of the Highway Police Division.
Wiroj Lakkhanaadisorn, a Move Forward Party list MP-elect, last week posted on social media that he was compiling evidence about the racket. He claimed overloaded trucks with special stickers were not being detained or the drivers arrested at weighbridges.
Pol Gen Damrongsak said, "Bribe-paid stickers have long been in use, despite suppression efforts. The matter has become explosive because it has been brought to the attention of society. All agencies concerned are now rushing to try and find out how many of them are currently being used."
He said he had instructed the Office of the Inspector-General and the CIB to jointly investigate the matter.
Pol Gen Damrongsak said the transfer of the Highway Police Division commander was to ensure the investigation could be carried out with transparency. The investigation would cover both the bribe givers, who might be transport operators, and those who received the payments, who might be state officials or their middlemen.
State officials found involved would face both criminal and disciplinary action, he said.
Police found guilty of involvement would face consequences, he said, adding that this year, to date, about 79 police officers had been sacked after being found involved in dishonest activities.
The national police chief said he had earlier already issued instructions for police to take tough action against overloaded lorries. Now that the matter had become big news, he would issue an official order for them to be more strict in enforcing legal weight limits.
A special committee would be set up to keep watch for those who turn a blind eye, or are lax in enforcing the traffic law, he said.
"The story about bribe-paid stickers is old, but has been posted on social media. Some posters may be ill intentioned toward police. I would like people to understand that police work hard from every aspect," Pol Gen Damrongsak said.