Former prime minister Yingluck Shinawatra seized the moment when the government's guard was down and with help from the likes of her brother, Thaksin, slipped out of the country undetected, army chief Chalermchai Sitthisad said Tuesday.
"Her escape had been well prepared and decided in advance. She waited for the right time and opportunity," said Gen Chalermchai, who is also the secretary-general of the National Council for Peace and Order (NCPO).
He rejected claims the army let her escape.
Gen Chalermchai told reporters that the former premier managed to elude authorities after she "abandoned all of her phones and changed her cars so it was hard to trace her using the same methods we did before", AFP reported.
Ms Yingluck failed to show up at the Supreme Court's Criminal Division for Holders of Political Positions last Friday to hear the ruling in the rice-pledging case, in which she was accused of dereliction of duty for failing to stop the losses and corruption which crippled the programme.
The court issued a warrant for her arrest following her no-show. She is believed to have fled to Dubai, where Thaksin lives in self-imposed exile.
The army chief admitted that there is still no clue to indicate how she escaped if indeed she fled the country.
"Someone such as the former prime minister has enough supporters and networks that would allow her to escape," said Gen Chalermchai.
She was also in touch with people knowledgeable in matters of national security who could help her slip out the country undetected, said the army chief.
He believed Mr Thaksin helped arrange Ms Yingluck's escape by arranging a private jet after she crossed by land or sea to a neighbouring country.
Meanwhile, he said, before she fled, the NCPO had slackened its monitoring of her after it had been criticised for causing intimidation, the army chief claimed.
The army chief denied claims the former premier was aided by senior figures in the current administration to leave the country, asking: "What would be an advantage of that?"
"If you say the NCPO or the army made a mistake in their supervising forces at border, I will accept it," the army chief said.
"Do not forget that the country's border is 6,656 kilometres long, with officers deployed only at important points."
Prime Minister Prayut Chan-o-cha said Tuesday he ordered officials to determine how she managed to flee the country.
"The order was given days ago. But various routes must be checked both domestically and internationally," the prime minister said, adding that the countries in contact include Singapore and the United Arab Emirates.
"I admit I am worried about what has happened, as is everyone. Officials are anxious because many people still attach importance to these powerful figures," the prime minister said.
"Please don't let what I have been trying to do for three years collapse so suddenly. You should trust me; I will not allow this case to collapse," Gen Prayut appealed to public, referring to Ms Yingluck's escape.
National police chief Pol Gen Chakthip Chaijinda said Interpol, which has a global membership of 190 countries, has been contacted to help locate the former premier.
Referring to reports that Ms Yingluck met 14 associates at a hotel on the night of Aug 23, Pol Gen Chakthip said work is under way to summon some of them for questioning.
Deputy national police chief Srivara Ransibrahmanakul said he on Monday questioned Pol Col Wathanyu Watcharapalothai, who served as personal security officer to Ms Yingluck.
Pol Col Wathanyu is an officer attached to the Special Branch's Intelligence Development Centre and was officially requested to provide security to Ms Yingluck for several years. He gave useful information, which could be pursued further, said Pol Gen Srivara.
Meanwhile, the Pheu Thai Party issued a statement saying that Ms Yingluck will probably offer an explanation for what has happened to the public when the time is right, a party statement read.
The party insisted it is still committed to its mission to serve its supporters regardless of Ms Yingluck's escape last Friday.