By Amy Sawitta Lefevre and Pairat Temphairojana
BANGKOK (Reuters) - Thousands of protesters surrounded Thailand's Interior Ministry and forced the evacuation of four others on Tuesday, intensifying their campaign to bring down the government of Prime Minister Yingluck Shinawatra.
The protesters defied a tough security law imposed late on Monday, after they had stormed two other ministries, to control demonstrations against Yingluck and her billionaire brother, former premier Thaksin Shinawatra.
Suthep Thaugsuban, the protest leader and a former deputy prime minister under the previous government, urged supporters to mount more blockades of government buildings on Wednesday, not only in Bangkok but across the country.
"Go to every ministry and make sure they are all surrounded, so they can no longer work for the Thaksin regime," Suthep told tens of thousands of flag-waving protesters in a late night speech at the Finance Ministry they have occupied.
As crowds swelled on the streets, Yingluck and her ruling Puea Thai Party were locked in a two-day confidence debate in parliament where they hold a commanding majority. The opposition has accused them of corruption and trying to pass laws to whitewash Thaksin of a graft conviction.
Civil servants fled as groups of demonstrators surrounded the interior, agriculture, tourism and transport ministries in blockades that have plunged Thailand into its deepest political uncertainty since it was convulsed by the bloodiest unrest in a generation in 2010.
"Getting rid of the Thaksin regime is not easy," Suthep told Reuters in an interview earlier. The demonstration "might be longer" than the three days originally planned, he said.
Thaksin is a former telecommunications tycoon who is hugely popular with poor urban and rural voters who have put him, or his party, into power in every election since 2001.
He was ousted in a 2006 military coup that was largely welcomed by Bangkok's middle class. He has hovered ghost-like over Thai politics since fleeing the country in 2008, accused of undermining the powerful monarchy, breaching conflict-of-interest laws and sentenced in absentia to two years in prison.
Though Yingluck, who opponents accuse of being a puppet for her brother, is expected to prevail in Thursday's confidence vote, it is unlikely to defuse a crisis fuelled by anger over the electoral and legislative power the Shinawatra family has long held, and is accused of abusing.
HERO AND VILLAIN
Thaksin remains a populist hero for many but is reviled by much of the Bangkok elite of generals, royal advisers, middle-class bureaucrats and business leaders who all largely back the opposition Democrat Party.
It is uncertain how long the confrontation will go on. Yingluck might, analysts say, seek to bolster her legitimacy by calling an election she would likely win, as Thaksin has done before, but that could be risky.
"She would first need to be absolutely sure there were no undemocratic forces preparing to fill the power vacuum that would be created," said Kan Yuenyong, director of the Siam Intelligence Unit think-tank.
"Right now, it's brinkmanship. The other side knows an election would only create another Thaksin government."
After forcing their way inside the Finance Ministry on Monday and bursting through the gates of the Foreign Ministry compound, 3,000 protesters circled the Interior Ministry, some wearing plastic bags to protect them from torrential rain.
They pushed up against the compound gates, some peering over a metal fence topped with razor wire and urged dozens of security guards to let them in. The crowd at the ministry dispersed by nightfall and returned to their main protest site in Bangkok's historic heart.
Staff were ordered to leave five ministries in all and protesters led a march towards the heavily barricaded Government House, Yingluck's offices. After a 15-minute standoff with police, they withdrew.
The uncertainty is driving foreign investors out of Thai financial markets, making the baht the second-worst performing emerging Asian currency in November having lost 2.7 percent this month. Thai stocks have retreated about 6 percent.
"Every time you think that Thailand is moving along, the government's ability to govern breaks down. We have gone through this many times since 2006," said JP Morgan analyst Matt Hildebrandt.
A court issued a warrant on Tuesday for the arrest of Suthep in connection with the raid on the Finance Ministry. Together with former Prime Minister Abhisit Vejjajiva, he has been charged with murder for allowing troops to open fire in 2010 protests by Thaksin's supporters.
A year later, their Democrat Party was routed in an election that swept Yingluck to power.
The confrontation is a reminder of the turmoil that has overshadowed Thailand for much of the last decade.
On one side is Thaksin, a former policeman who redrew the political map by courting rural voters to gain an unassailable mandate that he then used to advance the interests of major companies, including his own.
On the other is the elite and establishment, threatened by his rise. Thaksin's opponents include unions and academics who saw him as a corrupt rights abuser, and the urban middle-class who resented their taxes being used as his political war chest.
It is a confusing picture characterized variously as a class war, a rural-urban split, a clash between ancient and modern or a showdown between royalists and republicans.
Many anti-government protesters draw a distinction between themselves and the poor who are fiercely loyal to Thaksin.
"We are rich and our children are educated in Bangkok," said Nonthapan Suwananon, an anti-government protestor who manages an office. "They are poor, uneducated and have been bought out by Thaksin and his lot."
(Additional reporting by Panarat Thepgumpanat, Amy Sawitta Lefevre and Andrew R.C. Marshall; Writing by Jason Szep and Martin Petty; Editing by Robert Birsel)