By Robert Birsel
BANGKOK, May 24 (Reuters) - Thailand's military was due on Saturday to hold its first news conference since seizing power this week, amid signs opposition to the takeover could be gathering momentum, both from pro-democracy activists and supporters of the ousted government.
The army staged a coup on Thursday after failing to forge a compromise in a power struggle between a populist government and the royalist establishment, which brought months of sometimes violent unrest to Bangkok's streets.
Despite international calls for the restoration of democratic government, Army chief General Prayuth Chan-ocha has not promised a swift return to civilian rule, insisting there must be broad reforms and stability first.
"We must have economic, social and political reforms before elections," he told hundreds of civil servants on Friday in his first comments on his plans since the coup.
"If the situation is peaceful, we are ready to return power to the people," he added.
But reforms could take many months and stability could be elusive.
The news conference is expected some time on Saturday morning.
Thailand's political woes are the latest chapter in a nearly decade-long clash between the Bangkok-based establishment and Thaksin Shinawatra, a former telecommunications tycoon who broke the mould of Thai politics with pro-poor policies that won him huge support and repeated electoral victories.
Thaksin was ousted in a 2006 coup and left the country after a 2008 graft conviction but he remains Thailand's most influential politician and the guiding hand behind the ousted government of his sister, Yingluck Shinawatra.
The military detained Yingluck on Friday and a senior officer told Reuters she could be held for up to a week.
"We just need to organise matters in the country first," the officer told Reuters, declining to be identified.
STIRRINGS OF OPPOSITION
The military has banned gatherings of more than five people, censored the media and imposed a 10 p.m to 5 a.m. curfew but that has not stopped some people from showing their disapproval.
On Friday afternoon, several hundred people including students gathered in a central Bangkok shopping district in what appeared to be a spontaneous show of opposition to the takeover rather than support for Thaksin and Yingluck.
Soldiers dispersed the crowd and at least one person was detained, a Reuters witness said. A flurry of photographs on social media showed people holding up hand-written slogans such as "No Coup".
A small crowd also staged a protest in the northern city of Chiang Mai, Thaksin's hometown, a Reuters witness said.
The real danger for the military would be a sustained mass campaign by Thaksin's "red shirt" loyalists.
Thaksin's supporters in his northern and northeastern heartlands have repeatedly said they would act if another pro-Thaksin government was forced from power unconstitutionally.
Thaksin has not commented publicly since the coup. He has lived in exile since 2008 rather than return to Thailand to face a jail sentence for an abuse of power conviction.
Activists say a "red shirt" group is organising a protest in northern Bangkok on Saturday in defiance of martial law.
A resolute, well-financed campaign by Thaksin's red shirts, whose ranks include armed activists, would be a major test for the military.
The use of force to put down protesters could squander any legitimacy the military leaders may have after saying they took power in the first place to end violence and restore order.
A 2010 crackdown on Thaksin's supporters ended in serious bloodshed and damage to the army's image. Just over a year later a pro-Thaksin government was back in power after Yingluck's sweeping election victory. (Writing by Robert Birsel and Alan Raybould; Editing by Kim Coghill)