Prime Minister Prayut Chan-o-cha on Wednesday denied allegations of nepotism after the opposition accused his nephew of being involved in bid rigging in state procurement projects.
Speaking during a general debate in parliament on Wednesday, Gen Prayut said: "For any accusations of irregularities, let the justice system take its course.
"Stop trying to link my name with my relatives. I never dispense favours to anyone ... Why were you not so keen to speak about corruption in past [governments] as you are now?" Gen Prayut said.
"Efforts are being made to exploit these issues as part of election campaigning to woo voters. An investigation must be launched. I assure you that I won't be negligent.
"I urge you to respect the justice system. If you find anything suspicious, you can file complaints with the police," he added.
Gen Prayut was responding to the Pheu Thai Party MP for Roi Et, Jiraporn Sinthuprai, who took aim at his nephew during the general debate that kicked off on Wednesday.
The debate ends today without a vote.
It is the final grilling of the government before the House of Representatives' four-year term ends on March 23.
She claimed his nephew was granted the privilege of opening and operating a construction company on the grounds of Somdet Phra Eka Thotsarot Camp in Phitsanulok.
However, the company had to move from the military camp on Nov 3, 2016 following public criticism, Ms Jiraporn said.
She said a check found that despite the company operating at a loss between 2012 and 2013, it was still awarded three construction projects worth 28 million baht by the army in 2014.
Since the 2014 coup, the company has been awarded further projects, particularly in Phitsanulok and nearby provinces, which is under the jurisdiction of the 3rd Army Region, she said.
She added that the company was established with only 1.5 million baht of registered capital, but won high-value state project contracts.
The opposition MP said that registered capital reflects a company's financial standing and its credibility.
High amounts of registered capital show the company's ability to pay debts, she said.
She claimed that a check also found the company has no heavy construction machinery and only had 13 tools, despite operating in the construction business for more than eight years.
Ms Jiraporn also claimed the company was involved in bid rigging as competing bidders allegedly colluded to allow the company to win bids easily.
She also alleged the company had falsified accounts to avoid paying tax.
"Despite being awarded state projects worth up to a billion baht, the company remains in the red.
"While in the military camp, the company paid electricity and water bills of up to 200,000 baht per month.
"On moving out, the bills were only in the region of 1,000 baht per year. There may be some irregularities.
"I urge the prime minister to look into whether this was a case of cooking the books to avoid tax payments," Ms Jiraporn said.
"Gen Prayut once declared that combatting corruption is a national priority. Can you instruct state agencies to investigate the matter?" Ms Jiraporn said.
She also accused Gen Prayut's nephew of being involved in "so-called grey businesses" operated by Chinese triads in Thailand.
Previously, Rangsiman Rome, a Move Forward Party MP, said that a company run by an in-law of suspected crime boss Chaiyanat "Tuhao" Kornchayanant had rented at least 33 tour buses from the construction firm run by Gen Prayut's nephew.
Mr Rangsiman suspected these buses were used to transport Chinese nationals that were suspected of involvement in illegal activities in Thailand.
During the debate, Pheu Thai leader Cholnan Srikaew also accused the government of failing to curb the shady businesses operated by Chinese triads in the country.
"The grey businesses are now running rampant in the country. I thank Mr Chuvit who came forward to expose them,'' Dr Cholnan said.
He was referring to former massage parlour tycoon Chuvit Kamolvisit.
