The Thai government threatened on Sunday to impose a curfew in Bangkok after three days of fighting that has killed at least 24 people and spiralled into chaotic urban warfare, with both sides calling for reinforcements.
Prime Minister Abhisit Vejjajiva said a curfew was a possible step to restore order in the capital city of 15 million people known for its nightlife, as the army struggles to end weeks of increasingly violent protests seeking to topple his government.
"We cannot retreat now," Abhisit said on television.
The protesters remained defiant, demanding the resignation of the British-born, Oxford-educated Abhisit, who they accuse of colluding with Thailand's royalist elite and meddling with the judiciary to bring down previous elected governments.
"I will stay here. We will not flee," Jatuporn Prompan, a protest leader, told supporters in their 3.5 sq-km (1.2 sq-mile) encampment where at least 5,000 remain, including women and children, barricaded behind walls of tyres, poles and concrete.
On Sunday, a protester was shot in the head by a sniper on Rama IV road on the outskirts of the main protest site.
Hundreds of the red-shirted protesters have gathered on the road in working-class Klong Toey district since Saturday, many suffering gunshot wounds as they confronted nearby troops, hurling petrol bombs, rocks and crude homemade rockets.
They are burning walls of kerosene-soaked tyres to camouflage themselves in the billowing black smoke.
The bloodshed has been largely one-sided, as troops armed with automatic rifles easily dodge projectiles and open fire with automatic weapons. Some protesters have been killed by snipers positioned on the tops of office towers.
Soldiers can shoot if protesters come within 36 metres (120 ft) of army lines, said army spokesman Sansern Kaewkamnerd, adding more soldiers were needed to establish control.
No soldiers have been identified in the official tolls that show 24 people killed and 198 wounded.
Rain-slicked streets around the city remained tense. Near Victory Monument, where clashes took place on Saturday, a young man walking the street was shot in the head by a sniper's bullet, a Reuters witness said. He did not appear to be a protester.
New protest site
Hundreds massed in the Klong Toey area, apparently a strategic attempt to distract the army from its main task of clearing protesters from Bangkok's commercial district, a popular tourist and shopping area they have occupied for six weeks.
A night earlier, thousands massed in the Klong Toey area, creating a makeshift stage in what could be a new protest site.
If the protesters manage to establish control of a new area of the city, this would complicate the military's operation that began on Thursday when a series of checkpoints were set up and renegade soldier Khattiya Sawasdipol was shot in the head.
Many protest leaders now face terrorism charges that carry a maximum penalty of death, raising the stakes in a two-month crisis that has paralysed parts of Bangkok, stifled Southeast Asia's second-biggest economy and decimated tourism.
The protesters, who have adopted red as a protest colour and broadly support ousted premier Thaksin Shinawatra, set fire to vehicles and hurled rocks at troops who set up razor wire across deserted roads on Saturday in the business district.
Red shirt leader Nattawut Saikua told thousands still hunkered down in their main encampment late on Saturday that reinforcements were coming.
"We have been contacted by leaders in several provinces that they will mobilise to help us pressure the government," he said.
The U.S. Embassy has offered to evacuate families and partners of U.S. government staff based in Bangkok on a voluntary basis, and urged its citizens against travel to Bangkok.
"Is the government successfully dispersing the crowd and progressing toward ending the crisis? The answer is no, not so far, and it's a long way to go," said Thitinan Pongsudhirak, political scientist at Chulalongkorn University.
However, the government's strategy of starving protesters out of their encampment was shows signs of having an effect. Supplies of food, water and fuel were starting to run thin as the red shirt delivery trucks were being blocked.
But they said they still had enough to hold out for days.