By Amy Sawitta Lefevre and Pracha Hariraksapitak
BANGKOK, May 23 (Reuters) - Thai army chief General Prayuth Chan-ocha set out his plans for the country on Friday, a day after seizing power in a coup, saying reforms were needed before an election can be held and enlisting the help of the civil service.
Prayuth launched his coup after rival factions refused to give ground in a struggle for power between the royalist establishment and a populist government that had raised fears of serious violence and damaged the economy.
Soldiers detained politicians from both sides when Prayuth announced the military takeover, which drew swift international condemnation, after talks he was presiding over broke down.
The military summoned ousted Prime Minister Yingluck Shinawatra to a meeting and then banned her and 154 others, including politicians and activists, from leaving the country.
Prayuth also summoned hundreds of civil servants and told them he needed their help.
"I want all civil servants to help organize the country," he said. "We must have economic, social and political reforms before elections. If the situation is peaceful, we are ready to return power to the people."
Yingluck is the sister of Thaksin Shinawatra, a billionaire telecommunications tycoon turned politician who won huge support among the poor but the loathing of the royalist establishment, largely over accusations of corruption and nepotism. He was ousted as premier in a military coup in 2006.
Yingluck arrived at the army facility at noon, a Reuters witness said. Prayuth was there at the same time but there was no confirmation they had met.
After Prayuth had left, nine vans with tinted windows were seen leaving but it was not clear if Yingluck was in one of them or where they were going. An aide to a minister in the ousted government who declined to be identified said some people, including his minister, had been detained.
A former aide to Yingluck said she been out of telephone contact for several hours.
The military has censored the media, dispersed rival protesters in Bangkok and imposed an nationwide 10 p.m. to 5 a.m. curfew.
Yingluck was forced to step down as prime minister by a court on May 7 but her caretaker government, buffeted by more than six months of protests, had remained nominally in power, even after the army declared martial law on Tuesday.
Prayuth was expected to meet King Bhumibol Adulyadej at the royal palace in Hua Hin, south of Bangkok, to explain the army's move.
The armed forces have a long history of intervening in politics - there have been 18 previous successful or attempted coups since Thailand became a constitutional monarchy in 1932.
STUDENTS SHOW OPPOSITION
Bangkok was calm and life appeared normal, although the military ordered all schools and universities to stay closed.
But there were some signs of opposition to the takeover.
Small groups of students in Bangkok and Chiang Mai held up signs denouncing the coup and supporting democracy, according to witneses and pictures posted on social media.
Regular television schedules were suspended with all stations running military announcements interspersed with footage from the army's channel. It showed sites, now cleared, that had been taken over in and around Bangkok by political groups since anti-government protests flared in November.
Other footage showed people going about their business in different places with some saying they welcomed the coup.
International news channels were off the air and the military threatened to block provocative websites.
U.S. Secretary of State John Kerry said there had been no justification for the coup, which would have "negative implications" for ties with its ally, especially military ones.
"The path forward for Thailand must include early elections that reflect the will of the people," Kerry said in a statement.
He also called for the release of detained politicians.
There was condemnation from France, the European Union and the U.N. human rights office. Countries including Singapore and South Korea advised citizens against travel to Thailand.
The military briefed diplomats on Friday though some declined the invitation, apparently as a gesture of disapproval.
Prayuth is a member of the royalist establishment generally seen as hostile to the Shinawatras, although he tried for months to keep the army out of the strife and to appear even-handed.
He enjoyed cordial relations with Yingluck after she took office following a landslide election victory in mid-2011 but is regarded warily by some Thaksin supporters.
The army chief, who is 60 and due to retire later this year, has taken over the powers of prime minister but it was not clear if he intended to stay in the position.
An undercurrent of a crisis that is dividing rich and poor is deep anxiety over the issue of royal succession. King Bhumibol, 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 their loyalty to the prince.
MARKET REACTION MUTED
The anti-Thaksin protesters had demanded electoral changes that would end the Shinawatras' success at the ballot box. Thaksin or his parties have won every election since 2001.
Thaksin's "red shirt" supporters were dismayed and angry but said they had no immediate plans for protests. Those who had been protesting in Bangkok dispersed peacefully after the coup.
But many political analysts were predicting tension and violence. Protests would be a major test for Prayuth, who commands an army known to contain some Thaksin sympathizers.
In 2010, more than 90 people were killed in clashes, most when the army broke up protests against a pro-establishment government that had taken office after a pro-Thaksin administration was removed by the courts in 2008.
Investors have generally taken Thailand's upheavals in their stride and the market reaction to the coup was muted.
The baht was, at around 32.60 per dollar, firmer than its low point on Thursday of 32.70. The stock market opened down 2 percent but rallied to end 0.6 percent lower.
Thailand's economy contracted 2.1 percent in the first quarter of 2014 largely because of the prolonged unrest, which has frightened off tourists and dented confidence, bringing fears of recession. (Additional reporting by Apornrath Phoonphongphiphat, Aukkarapon Niyomyat and Bangkok bureau; Writing by Robert Birsel and Alan Raybould; Editing by Alex Richardson and Nick Macfie)