In a chilling move apparently aimed at neutralizing critics and potential opposition, Thailand's new army junta on Saturday ordered dozens of outspoken activists, academics and journalists to surrender themselves to military authorities.

The junta, which is already holding most of the government it ousted in a coup Thursday in secret locations against their will, said it would keep former prime minister Yingluck Shinawatra and others in custody for up to a week to give them "time to think" and keep the country calm.

Two days after the army seized power in the nation's first coup in eight years, it also faced scattered protests that came amid growing concern over the junta's intentions. Also Saturday, the military dissolved the Senate — the last functioning democratic institution left, and absorbed its legislative powers.

Canada condemns coup Foreign Affairs Minister John Baird on the Thai army's seizure of power: "This decision violates Thailand's democratic principles and stands in stark contrast to the Army's earlier assurances that its role would be limited to securing public order. "We hope and expect the Thai military will return Thailand to civilian rule as soon as possible, respect democratic processes and the rule of law, ensure freedom of expression and assembly, and guarantee due process for those who have been detained."

"Military rule has thrown Thailand's rights situation into a free fall," said Brad Adams, Asia director at Human Rights Watch. "The army is using draconian martial law powers to detain politicians, activists and journalists, to censor media, and to ban all public gatherings. This rolling crackdown needs to come to an end immediately."

At least 100 people, mostly top politicians, have been detained incommunicado so far. Deputy army spokesman Col. Weerachon Sukondhapatipak said they were all being well-treated and the military's aim was to achieve a political compromise.

Weerachon said all those held have had their cellphones confiscated because "we don't want them communicating with other people. We want them to be themselves and think on their own."

"This is because everybody involved in the conflict needs to calm down and have time to think," Weerachon said. "We don't intend to limit their freedom — it's to relieve the pressure."

In a military order broadcast at the start of the day, the junta summoned 35 more people, including politicians, political activists and, for the first time, outspoken academics and some journalists.

One of those on the list, Kyoto University professor of Southeast Asian studies Pavin Chachavalpongpun, said by telephone from Japan that he would not turn himself in. He said the summons meant the junta felt insecure.

"The military claiming to be a mediator in the Thai conflict, that is all just nonsense," said Pavin, who is frequently quoted by foreign media as an analyst. "This is not about paving the way for reform and democratization. We are really going back to the crudest form of authoritarianism."

Half a year of political turmoil

In the evening, the junta broadcast its sixth official order, for a single journalist: Pravit Rojanaphruk, an outspoken columnist for the English-language daily The Nation, who was summoned to report to the army at 10 a.m. Sunday. In a tweet Saturday night, Pravit was defiant, saying "the more they exercise their illegitimate power the more illegitimate they become."

The junta also ordered banks to freeze the assets of two top politicians it had summoned but who remain in hiding, including the ousted education minister and the chief of the former ruling party.

An anti-coup protester, right, is detained by a Thai police officer during a protest on a street in Bangkok, Thailand Saturday, May 24, 2014. (Wason Wanichakorn/Associated Press)

Gen. Prayuth Chan-ocha, who leads the junta, has justified the coup by saying the army had to act to avert violence and end half a year of political turmoil triggered by anti-government protests that killed 28 people and injured more than 800.

The intractable divide plaguing Thailand today is part of an increasingly precarious power struggle between an elite, conservative minority backed by powerful businessmen and staunch royalists based in Bangkok and the south that can no longer win elections, and the political machine of exiled former prime minister Thaksin Shinawatra and his supporters in the rural north who backed him because of populist policies such as virtually free health care.

The army deposed Thaksin in a 2006 coup. And on Friday, it detained his sister, Yingluck, who was forced from office earlier this month by a controversial court verdict for abuse of power, which she denies.

The ruling party, which rose to power in a landslide election in 2011 that was deemed fair, had insisted for months that Thailand's fragile democracy was under attack from protesters, the courts and, finally, the army which together had rendered it powerless, step by step.

Although Thailand has been calm since the coup and there is little military presence on the streets, small-scale protests against the junta have been reported in the northern city of Chiang Mai, Khon Kaen in the northeast, and the beach resort of Pattaya just south of Bangkok.

Anti-coup protests

In the capital, life largely went on as normal. But hundreds of anti-coup protesters took to the streets for a second straight day, defying an army-imposed edict banning groups larger than five from gathering for political purposes. They shouted slogans demanding a return to civilian rule and waved signs outside a cinema complex before moving on to Victory Monument, a major city landmark several kilometres away.

Thai Army chief General Prayuth Chan-ocha said he had to act to restore stability. (Athit Perawongmetha/Reuters)

The demonstrators briefly confronted rows of soldiers and police lined up with riot shields on a road leading to the monument, with a few scuffles breaking out before most of the protesters broke away. By late afternoon, about 500 demonstrators had gathered at the moment. Army and police presence was low key, and the groups dispersed before a 10 p.m. curfew came into effect.

Several demonstrators have been detained, and rights groups have expressed concern over the growing repression.

Thailand travel advisory There is no nationwide advisory in effect for Thailand. However, travellers should exercise a high degree of caution due to ongoing large-scale political demonstrations in Bangkok and elsewhere in the country. There have been multiple incidents of violence associated with these protests, which have resulted in injuries and fatalities, including in areas adjacent to popular tourist sites and commercial centres in Bangkok. The risk of further violence remains high.

"This is a dangerous precedent — people simply expressing opinions must not be penalized," said Richard Bennett, Amnesty International's Asia Pacific Director. "The need for the military to exercise restraint is particularly crucial given that demonstrations calling for civilian rule could intensify."

The army launched the coup after ordering two days of brief peace talks in which the country's political rivals failed to end their deadlock. Anti-government protesters had been calling for the army to intervene and support their bid to overthrow the government, which they accused of corruption, since November.

Multiple nations have condemned the coup. The U.S. State Department urged "the immediate restoration of civilian rule and release of detained political leaders, a return to democracy through early elections, and respect for human rights and fundamental freedoms."

Washington also said it had cancelled ongoing military exercises, and a firearms training program for the Thai police. Pentagon press secretary Rear Adm. John Kirby said U.S. law and "our own democratic principles" require the U.S. to reconsider its long military relationship with the Southeast Asian country.

The Pentagon is also cancelling the June visit of U.S. Pacific Fleet Commander Admiral Harry Harris to Thailand and is withdrawing the invitation to the commander general of the Royal Thai Armed Forces to visit U.S. Pacific Command in June, Kirby said.

Underscoring the challenges facing Thailand's new rulers, police on Saturday said suspected Islamic insurgents detonated at least nine bombs in the country's restive south, killing two people and wounding at least 52. Pattani provincial police chief Phote Suaisuwan said the blasts hit four 7-Eleven convenience stores, two gasoline stations and three other locations.

It was unlikely that the blasts were related to the coup, though insurgents may have been emboldened by the dramatic development. More than 5,000 people have been killed since the insurgency flared in 2004 in Thailand's predominantly Muslim south.