Prime Minister Prayut Chan-o-cha said he knows which country former premier Yingluck Shinawatra is hiding in after fleeing her criminal negligence case last month and that extradition proceedings will begin if the court finds her guilty in today's verdict, scheduled to start at 9am.
Ms Yingluck failed to show up at the Supreme Court's Criminal Division for Holders of Political Positions on Aug 25, compelling it to reschedule the ruling on her rice-pledging case.
Speculation is rife that she sneaked out of the country via Cambodia and Singapore and has holed up overseas, possibly in Dubai with her older brother Thaksin, another fugitive former premier.
"I've said I know [her whereabouts] but I'll still not tell you," Gen Prayut said to reporters. "After Sept 27, I will tell you where she is."
"I have spies," he said.
The prime minister said Ms Yingluck may have been assisted in her escape by her former subordinates.
Gen Prayut said he had learned of Ms Yingluck's whereabouts from his secret agents, adding he was still awaiting confirmation from authorities there.
He said it was important to first verify whether the country would send her back to Thailand if requested.
If Ms Yingluck is found guilty today the government would require the assistance of Interpol to find and apprehend her, he added.
Gen Prayut said there was no indication she had sought political asylum overseas.
The prime minister said her passport could be revoked if a guilty verdict is handed down today.
Referring to the three police officers who allegedly abetted her escape, Gen Prayut said they could face criminal charges.
However, in earlier remarks officials said the only crime they were guilty of was supplying a car with a counterfeit registration plate as their actions occurred before an arrest warrant for Ms Yingluck was issued.
"We must look at their intentions," he said.
Pol Col Chairit Anurit, former deputy commander of Metropolitan Police Division 5, and two other lower-ranking officers from the provincial police office in Nakhon Pathom province, have been accused of helping Ms Yingluck flee.
A police panel has been set up to conduct a thorough investigation.
They have been charged so far with using fake plates on a vehicle that is believed to have taken her outside the capital.
Pol Maj Gen Panurat Lakboon, deputy chief of the Metropolitan Police Bureau (MPB), said the investigation is expected to conclude within seven days.
Speaking of security measures at the Supreme Court for today's ruling, city police chief Sanit Mahathavorn said barricades will be set up to prevent supporters of the former premier from flooding the court building.
Three checkpoints will be set up on routes leading to the court, he said, adding security plans have been put in place despite growing fears Ms Yingluck may again stage a no-show.
Norawit Lalaeng, Ms Yingluck's lawyer, said he has not been contacted by Ms Yingluck or informed whether she plans to make an appearance. Regardless of her decision, judges can read the verdict in absentia, he noted.
Somkid Chuakong, a former Pheu Thai MP for Ubon Ratchathani, said 200 to 300 of her supporters will converge on the court today but no violence is expected.
Surasak Threerattrakul, director-general of the Office of the Attorney-General's Investigation Office, said the ruling hearing is scheduled for the early morning.
However, it was unclear how long it would take for the verdict to be read out as Thai courts are known for giving lengthy explanations of their rulings.
