THAI army chief General Prayuth Chan-ocha tightened his grip on the country today.

The military summoned ousted prime minister Yingluck Shinawatra to a morning meeting and then banned her and 154 others, including politicians and activists, from leaving Thailand.

But it did not end there. Ms Shinawatra was detained at the end of the brief meeting by soldiers and placed under house arrest at her Bangkok home.

Among the officials who showed up for the meeting at an army compound in Bangkok was her temporary replacement, Niwattumrong Boonsongpaisan.

By nightfall, dozens of the VIPs who turned up for the meeting were still being held, although at least eight ex-cabinet ministers were released.

The coup leader also summoned hundreds of civil servants and told them he needed their help.

"I want all civil servants to help organise the country," he said. "We must have economic, social and political reforms before elections.”

The anti-Thaksin yellow-shirt protesters had demanded reforms that would end the Shinawatras' success at the ballot box. 

Their Rak Thai party has won every election since 2001 with the support of the rural peasantry, to the dismay of the urban royalist establishment.

The general is seen as a member of that establishment, although he tried for months to keep the army out of the strife.

He claimed yesterday that, if the situation remained peaceful, “we are ready to return power to the people," a statement which was somewhat undermined by the ex-president’s arrest.

General Prayuth met King Bhumibol Adulyadej at the royal palace to explain his actions but the outcome was not reported.

Bangkok appeared calm and life seemed normal, although the military ordered all schools and universities to shut.

But several hundred people including students gathered in a central shopping district, despite a ban on protests, to voice their opposition to military rule. Some waved signs reading "no coup" and "get out, dictators," until the military dispersed the protest.

About 80 protesters also gathered briefly in the northern city of Chiang Mai to denounce the coup and call for an election.