Thailand's military summoned the deposed cabinet and ruling-party leaders to report Friday to a new junta that seized power a day earlier in a coup which has triggered US-led international censure.

Claiming to act to halt months of deadly political turmoil, a new military regime under the tough-talking army chief declared a nationwide night-time curfew, curbs on civil liberties, and ordered masses of rival demonstrators off Bangkok's suddenly hushed streets.

The junta headed by General Prayut Chan-O-Cha suspended most of the constitution, drawing rebukes from Washington, Europe, and the UN Secretary-General, who all called for civilian control to be restored.

Members of the now ousted Cabinet, along with leaders of the Puea Thai party that had been in power, were told to report to the military in central Bangkok at 10:00 am (0300 GMT) Friday.

Prayut had said Thursday the coup was staged "in order for the country to return to normal quickly."

"All Thais must remain calm and government officials must work as normal," he said in a brief televised address announcing the takeover, flanked by top military and police officials.

It remained unclear what awaited members of the ousted government if they turned up.

But moments before the coup, leaders of Puea Thai and their Democrat Party foes along with each side's rival protest leaders were taken away by the military from Bangkok talks called by Prayut to bridge their differences.

Their whereabouts remained unknown early Friday.

- 'No justification' -

US Secretary of State John Kerry said there was "no justification" for a coup that would have "negative implications" for US relations.

He called for "early elections that reflect the will of the people," while the Pentagon said it was reviewing military cooperation with its Southeast Asian ally.

Thailand has been locked in a nearly decade-long political crisis since a 2006 military coup that deposed controversial tycoon-turned-politician Thaksin Shinawatra as premier.

Since then, a power bloc centred on Thaksin's family has battled for primacy with a Bangkok-based royalist camp closely tied to the powerful military.

Thailand's democratic development has now been interrupted by 19 actual or attempted coups since 1932, interventions that traditionally require the monarchy's approval.

It was unclear whether the palace had blessed Prayut's coup.

Some observers see the crisis as a struggle to decide who will run the country when the more than six-decade reign of ailing, 86-year-old King Bhumibol Adulyadej eventually ends.

Backers of the royalist elite have engaged in several months of escalating confrontation with the democratically elected government that saw Thaksin's younger sister Yingluck dismissed as premier earlier this month by a controversial court ruling.

Yingluck and three of Thaksin's other relatives were among those told to report to military authorities Friday morning.

Thaksin lives in exile after a corruption conviction, but his camp retains strong support particularly in rural northern Thailand, and has won every general election since 2001, to the dismay of its military-allied rivals.

Experts at the Siam Intelligence Unit, a Bangkok-based think-tank, expect an interim premier to be named and the junta to rule for up to two years and draft a "draconian" new constitution.

Some fear more turmoil.

"The coup is not a solution at all to end the crisis. This will become the crisis," said Pavin Chachavalpongpun of the Centre for Southeast Asian Studies at Japan's Kyoto University.

"It shows the military has never learned the lesson from 2006," he said, referring to the cycle of instability stemming from Thaksin's overthrow.

Violence related to nearly seven months of anti-Thaksin protests have left at least 28 dead and hundreds wounded.

- Jubilation and dismay -

Caretaker premier Niwattumrong Boonsongpaisan was among ministers ordered to report to the army. His whereabouts were unknown.

But Chalerm Yubamrung, a Thaksin insider and labour minister until recently, was detained Thursday by the military, his son Doung Yubamrung said.

Prayut declared martial law on Tuesday, giving the military draconian powers.

With the coup, all television and radio stations including foreign broadcasters were ordered to air only a steady stream of army announcements and the junta warned it would block social media platforms that carry anti-coup content.

UN Secretary-General Ban Ki-moon was "seriously concerned," his spokesman said. He urged a return to "constitutional, civilian, democratic rule."

Prayut gave no indication how long the military would rule. It kept the reins for more than a year after the 2006 coup.

Anti-Thaksin protesters had demanded the removal of the government and the his clan's influence in politics, alleging deep corruption.

It was not immediately clear how the pro-Thaksin "Red Shirt" protesters would respond. Its leaders had said a coup could trigger civil war, but there were no immediate reports of unrest.

The coup -- which sent commuters scurrying to get home before Thursday's 10 pm curfew -- elicited jubilation from opposition protesters and dismay from government supporters.

"Our country has been chaotic and has had no solutions for a long time," said office worker Arnusit Chenruk, 39, calling the coup a "good" thing.