Thai coup leader General Prayuth Chan-ocha said on Monday he had been formally endorsed by the king as head of a military council that will run the country, and warned he would use force if political protests flared up again.
Prayuth seized power on May 22, saying the army would restore order after nearly seven months of sometimes deadly street demonstrations. The military has since taken into custody of scores of politicians, activists, academics and others.
"Will we go back to where we were before? If you want to do that, I will need to use force and impose the law strictly," Prayuth said in a statement he read on television. "You will have to forgive any tough measures as they are necessary."
He did not set a timeframe for how long the army would stay in power, although he said he hoped to hold elections soon.
The royal endorsement is a significant formality in Thailand, where the monarchy is the most important institution.
Prayuth's address is likely to provoke conflicting reaction in a country polarized by nearly a decade of rivalry between the royalist establishment, of which Prayuth is a member, and Thaksin Shinawatra, a populist tycoon who broke the political mold.
Prayuth, wearing a formal white dress uniform, said he would set up a council of advisers but gave no details on the form of the new government that will run the country under his military junta, the National Council for Peace and Order.
"The country needs a prime minister. If we go back and look at the past there is a way to do this but there might be some changes to the process in order to create legitimacy," he said.
The military ousted the remnants of a government that had been led by Prime Minister Yingluck Shinawatra, Thaksin's sister, until she was removed by a court on May 7 for abuse of power.
It has taken over with a heavy hand, throwing out the constitution, dissolving the Senate and censoring the media. Anyone who insults the monarchy or violates the military's orders will be tried in a military court.
Despite warnings, small crowds of people voicing opposition to the coup have been gathering in Bangkok as well as in the north and northeast, strongholds of the ousted government.
About 1,000 people thronged around Victory Monument, a central Bangkok hub, on Sunday, occasionally confronting lines of soldiers with riot shields, but there have been no clashes.
The army has allowed Yingluck to go home, although she remains under military supervision, said a senior military official who declined to be identified.
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"She is free to come and go as she pleases but will have to inform us as a sign of mutual respect and we will have soldiers guarding her home," the officer said on Sunday.
Suthep Thaugsuban, who led the Bangkok protests that undermined Yingluck's government from last November, was released from army custody on Monday but taken with 12 associates to the Attorney General's office. Suthep faces a charge of insurrection relating to the protests but was granted bail, said a member of his legal team.
The easing of restrictions on Yingluck will do little to dispel concern among her supporters that the military is intent on a crackdown for reasons other than restoring order and ending antagonism between protesters backed by the establishment and the real power behind her government, her brother and former premier Thaksin.
Thaksin was ousted in a 2006 coup after big-spending policies had won him the passionate support, and votes, of the poor but the animosity of the establishment, who saw him as a corrupt, authoritarian opportunist and a threat to the old order.
Thaksin was also accused of being disrespectful to the monarchy and even a closet republican, which he denied.
The former leader has said on Twitter he was saddened by the latest events, and called on the army to treat everyone fairly. Thaksin has lived in self-exile since a 2008 graft conviction.
The crisis between the establishment and Thaksin comes amid anxiety over the issue of royal succession. The king, the world's longest-reigning monarch, is 86 and spent the years from 2009 to 2013 in hospital.
Crown Prince Vajiralongkorn does not command the same devotion as his father, but some Thaksin supporters have recently been making a point of showing their loyalty to the prince.
Meanwhile, one Thaksin ally, ousted Education Minister Chaturon Chaisang, said he expected the military to implement steps aimed at sidelining once and for all Thaksin, his family and his allies, and blocking forever his formidable political machine, which has won every election since 2001.
"Any election after that would be meaningless," Chaturon told Reuters by telephone from an undisclosed location on Sunday, referring to changes he expects the military to implement.
"The system will be designed so no matter which party people vote for, it won't be able to form a government."
For now, the military is focusing on getting the economy back on track and ending dissent.
Shares in building contractors jumped more than 3 percent on Monday on expectations the new military government would speed up disbursements for infrastructure projects that were put on hold during the months of political unrest.
Among them, Italian-Thai Development, the country's largest construction firm, rose 0.5 percent even though the army has summoned its president, Premchai Karnasuta, to appear before it on Monday.
In its latest such order, it told 38 people to come in, including political associates of Thaksin and several big business allies of the former telecommunications tycoon.