BANGKOK (Reuters) - Anti-government protesters forced their way inside Thailand's Finance Ministry and burst through the gates of the Foreign Ministry compound on Monday, in an escalating bid to overthrow Prime Minister Yingluck Shinawatra.
The seizing of government buildings by protesters, led by the opposition Democrat Party, plunges Thailand into its deepest political uncertainty since it was convulsed three years ago by the bloodiest political unrest in a generation.
The protesters' actions "threaten the stability of the government," Yingluck said in a brief televised address.
The protesters accuse Yingluck of being a puppet for her brother, former Prime Minister Thaksin Shinawatra, who was ousted in a 2006 military coup and convicted two years later of graft - charges he denies. Thaksin lives in self-imposed exile but exerts enormous influence over his sister's government.
About 1,000 protesters swarmed the Finance Ministry, filling its cavernous marble-floored halls and occupying six other buildings. Many gathered in first-floor meeting rooms, blowing whistles and laying out plastic mats for resting and eating. Occupying its grounds is symbolic, they said, of targeting the money at the heart of the "Thaksin regime".
Staff left, moving into a parking lot before leaving.
"I invite protesters to stay here overnight at the Finance Ministry," protest leader Suthep Thaugsuban told the crowd.
"Our only objective is to rid the country of the Thaksin regime," added Suthep, a former deputy prime minister under the previous Democrat-led government.
Yingluck, 46, was defiant, saying she would not step down.
Her broad support in Thailand's vote-rich north and northeast - rural regions that are among the country's poorest - helped her win a 2011 election by a landslide, making her Thailand's first woman prime minister.
That election was seen as a defeat for the traditional Bangkok elite of generals, royal advisers, middle-class bureaucrats and business leaders - a group that backs the Democrats and deeply mistrusts Thaksin and his sister.
After two years of relative calm, tension between those factions is rising quickly, reviving memories of a tumultuous 2008 when anti-Thaksin "yellow shirt" protesters shut Bangkok's airports and held crippling rallies against two Thaksin-backed governments, which were eventually disbanded by a court.
Although Thaksin or his allies have won every election in the past decade, the judiciary often undercuts him, illustrating how the billionaire former telecommunications tycoon and populist hero remains one of the most polarising figures in modern Thai history.
Since the 2006 coup, court rulings have removed two prime ministers, disbanded four parties, jailed three election commissioners and banned 220 politicians.
The military will be watched closely. A major force in politics since Thailand became a democracy in 1932, the military has staged 18 coups - some successful, some not - and made several discreet interventions in forming coalition governments, almost all with the tacit backing of the royalist establishment that now reviles Thaksin.
Yingluck said an Internal Security Act would be extended in Bangkok and some surrounding areas including in Samut Prakarn province, in which Bangkok's main airport is located. But she said the government would not use force on protesters occupying government buildings.
The act allows troops to impose curfews, operate checkpoints and restrict movements of protesters.
There were almost no police at the Finance Ministry when the protesters swarmed in, witnesses said.
"The government cannot use force at this juncture. If they do, they will lose immediately," said Boonyakiat Karavekphan, a political analyst at Ramkamhaeng University in Bangkok. "The government's only option now is to let the occupations happen and to refrain from touching the protesters."
Suthep said the Finance Ministry would be a "second stage" in a protest that began on October 31 and had been mostly confined to Bangkok's historic quarter, where about 100,000 people gathered on Sunday.
That was the largest demonstration since April-May 2010, when Thaksin's mostly rural "red shirt" supporters tried to bring down a Democrat-led government. Those protests were eventually quelled by a military crackdown in which 91 people, most of them Thaksin supporters, were killed.
On Monday, the protesters began the day chanting "Get Out!" against the government as they fanned out to state offices, military and naval bases and state television channels.
The tension condemned the baht currency to an 11-week low, down 0.4 percent to 31.97 to the dollar. Thailand's benchmark stock index .SETI lost 0.5 percent to its lowest since September 6, taking its year-to-date loss to 2.8 percent.
The protests were sparked last month by a government-backed amnesty bill that could have allowed Thaksin to return without facing jail time for a 2008 corruption sentence.
Although the bill has been dropped, the demonstrations have expanded into an all-out call for the ouster of Yingluck, who faces a no-confidence debate on Tuesday that she'll likely pass easily given her Puea Thai Party's parliamentary majority.
She said the protests could hurt tourism and investor confidence and she would not dissolve the house.
Suthep exhorted the crowd to also seize the government's Public Relations Department, a few blocks from the Finance Ministry. By afternoon, about 500 protesters were inside the grounds but not inside the building, which is controlled by the office of the Prime Minister.
By early evening, they had also overrun the Foreign Ministry's compound.
Thaksin won elections in 2001 and 2005 by landslides but corruption scandals steadily eroded his popularity among Bangkok's middle class.
Yingluck's party received a blow last week when the Constitutional Court rejected proposals to make the Senate fully elected - a move that could have strengthened her government.
Supporters of Thaksin and Yingluck gathered in a stadium at the opposite end of the city, about 15 km (9 miles) away. They say the court verdict is the latest attempt by anti-Thaksin forces to thwart the legislative process. (Additional reporting by Pracha Hariraksapitak, Aukkarapon Niyomyat, Viparat Jantraprap and Kittiphong Thaichareon. Writing by Jason Szep. Editing by Robert Birsel)