The red-shirted supporters of ousted premier Thaksin Shinawatra retreated from parliament, but tens of thousands have remained in Bangkok's main shopping district since Saturday, defying Prime Minister Abhisit Vejjajiva's orders to leave.
Protesters immediately threatened to challenge the decree, which gives the army broad powers, lets the authorities suspend certain civil liberties, bans public gatherings of more than five people and stops media reporting news that "causes panic.”
"We will declare war," Arisman Pongruangrong, a protest leader, told supporters, urging followers in rural provinces to mass at city halls. "No more negotiations," he said.
The "red shirts" say that on Friday they will hold their biggest protest yet. But military checkpoints would be set up oustside Bangkok to stop any from entering the city, Deputy Prime Minister Suthep Thaugsuban said on television.
Despite the security clampdown, a crowd of up to 50,000 in the shopping district cheered and applauded fiery speeches by "red shirt" leaders into the night. Many had no plans to leave and were setting up to sleep, some on cardboard boxes.
Suthep said soldiers would be dispatched to guard key areas. That came after Abhisit, operating from a military base doubling as a safe house, assured the public he would not use force.
"The government's goal is to help the situation return to a normal way of life, to maintain the sanctity of the law," he said in a televised statement hours after the siege of parliament.
The scene outside parliament was among the most chaotic and confrontational since the protests began on March 12.
Protesters massing outside the gates of the sprawling complex pressed up against a line of police in full riot gear.
When some "red shirts" forced open the iron gate, police melted away and hundreds swarmed into the grounds, including dozens packed on a truck that drove through the main entrance.
They pressed up against security forces outside the lobby doors but left after about 20 minutes, only to regroup outside the gates, brandishing guns and tear gas canisters they said were seized in scuffles with military police.
Ministers had earlier held a cabinet meeting at parliament.
Some, including Abhisit, had left before the protesters broke through, but Suthep and several other ministers had to scale a wall in the compound and escape by military helicopter.
"We have achieved our mission today," Korkaew Pikulthong, a "red shirt" leader, told the crowd through a bullhorn.
Despite the tension, Thai stocks and the baht currency rose on confidence the government, with support from the military and the royalist establishment, would survive the showdown with the mostly rural and working class protesters.
Foreign investors have been ploughing money into the fast-recovering economies of Southeast Asia and have not left Thailand out despite the turbulence. Since Feb. 22, foreigners have bought a net $1.73 billion of Thai stocks.
However, Finance Minister Korn Chatikavanij said prolonged protests could cause growth in the economy, Southeast Asia's second biggest, to be "significantly worse" than a government projection of 4.5 percent. And the unrest could also delay an expected interest rate rise.
Another month of protests, he said, .”.. would be intolerable, not only to the economy as a whole but for the sanity of Bangkokians.”
Abhisit faces pressure from Bangkok's elite and middle class and even his own government to halt the rally, but has held back to avert a confrontation many believe would cause greater damage.
Threats to arrest the protesters have not been carried out, emboldening a movement that has tapped an undercurrent of frustration over a level of income disparity that ranks among Asia's widest, according to World Bank statistics..
Army chief Anupong Paojinda, central in Thailand's balance of power, said there was no justification to use force to disperse the crowds, an unidentified source told the Bangkok Post.
"We can't since it will cause losses," the source quoted Anupong as telling the prime minister. "They all are Thais." The "red shirts" have taken aim at the urbane, 45-year-old Oxford-educated Abhisit, whom they see as a front man for an unelected elite and military intervening in politics and operating with impunity.
They say Abhisit lacks a popular mandate after coming to power in a 2008 parliamentary vote following a court ruling that dissolved a pro-Thaksin ruling party. They want immediate elections that Thaksin's allies would be well placed to win.
They have won new support from Bangkok's urban poor but have angered middle classes, many of whom regard them as misguided slaves to Thaksin, a wily telecoms tycoon who fled into exile to avoid a jail term for graft.
Abhisit has offered to dissolve parliament in December, a year early. On Wednesday, he canceled a trip to Washington next week to attend an international nuclear summit, although he planned to join a regional leaders summit in Hanoi on Thursday.
