BANGKOK : Thailand's military junta said on Saturday detained former premier Yingluck Shinawatra and other ousted government leaders would be held for up to a week, tightening its grip following a coup that has provoked an international outcry.

As sporadic protests flared in Bangkok, the military also said the seizure of the government by General Prayut Chan-O-Cha had been ‘acknowledged’ by the country's revered king, while stopping short of calling it a royal endorsement. Briefing the media for the first time since Prayut deposed the civilian government Thursday after months of escalating political turmoil, the military declined to specify the whereabouts of Yingluck and scores of other prominent detainees, but said they were in no danger.

‘They will be detained for up to one week depending on how directly they were involved (in Thailand's political tumult),’ army spokesman Colonel Winthai Suvaree told reporters. In comments to AFP, Lieutenant General Thirachai Nakwanich, head of the military command for central Thailand including Bangkok, added: ‘(Yingluck) is under detention, and she is fine.’

Prayut had submitted a letter to King Bhumibol Adulyadej on the takeover, said a separate military announcement read out later on national television.

The 86-year-old king commands great respect among his subjects, and his blessing is traditionally sought to legitimise Thailand's recurring military takeovers. The palace ‘replied that his Majesty has acknowledged (the letter),’ the brief bulletin said.  The palace itself has not issued a statement on the coup yet.

Washington, which has led criticism of the coup, took its first concrete steps, suspending $3.5 million in military assistance to its ally - about one-third of its Thai aid. Further cuts were being considered.

Civil liberties have been curbed, media restrictions imposed, most of the constitution abrogated, and rival political protesters cleared from Bangkok's streets. A night-time curfew has tamed the capital's rowdy night-life, further chilling a vital tourist sector already cooled by the long-term strife.

Yingluck and scores of other figures in the now-deposed government and her Puea Thai party - plus many of their fierce rivals - were called in Friday as the army corralled potential opponents of the coup. They were taken in under a martial law provision allowing detentions of up to seven days without charge. It was not known whether any charges were being prepared.