Prime Minister Prayut Chan-o-cha vowed Tuesday to take tough action against any police officers found guilty of involvement in position buying within the police force.
He was responding to claims by former Democrat MP Witthaya Kaewparadai that the practice was rampant in police transfers and promotions last year.
Gen Prayut thanked Mr Witthaya for drawing attention to the issue and providing information on it, saying he has received many complaints about corruption of this kind.
"This time, [those responsible] must be caught," Gen Prayut said.
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His remarks come as Pol Lt Gen Thesa Siriwatho, the chief of Provincial Police Region 8, was recently transferred to an inactive post pending an investigation into his alleged role in position buying.
Deputy Prime Minister Prawit Wongsuwon, who oversees the Royal Thai Police, said Tuesday there were reasonable grounds for the probe and transfer.
"Anyone involved in position buying will be dealt with," he said.
But Gen Prawit dismissed as baseless claims by Mr Witthaya that position buying is rife among Bangkok police.
Pol Lt Gen Thesa has been transferred to the Royal Thai Police Operations Centre until further notice.
A fact-finding committee will be set up to look into the allegations against him. National police chief Chakthip Chaijinda ordered the transfer to take effect on Monday.
Pol Lt Gen Thanet Phinmuangngam, an assistant national police chief, has been appointed acting chief of Provincial Police Region 8.
Pol Lt Gen Thesa is believed to have close ties with Suthep Thaugsuban, the former leader of the disbanded People's Democratic Reform Committee protest group.
Pol Maj Gen Nithas Limsiriphan, deputy commander of the Royal Thai Police's Office of Human Resources, asked the police inspector-general to report the findings to the police chief within 15 days.
Meanwhile, Metropolitan Police Bureau chief Sanit Mahathavorn denied Mr Witthaya's claim that position buying was twice as high among city police as in Provincial Police Region 8.
On Monday, a deputy police spokesman said preliminary inquiries would first determine whether the claims were true.