Tensions still high
Al Jazeera's Wayne Hay, reporting from Bangkok, said the red shirts were in fact fortifying their encampment on Tuesday amid tougher rhetoric from the military, indicating that troops may be getting ready to clear them from the city's main shopping and tourist area, where they have camped since April 3.
Colonel Sansern Kaewkamnerd, an army spokesman, said on Monday that "we are left with no choice but to enforce the law".
"Those who do wrong will get their punishment. Taking back the area along with other measures are all included in enforcing the law. All this must be done," Sansern said.
The spokesman added that soldiers "have the right to carry weapons to protect themselves, and [I] believe the society finds it acceptable".
With the increasing pressure and intensifying rhetoric, a confrontation was "going to happen sooner or later", our correspondent said.
He added, however, that the red shirts, who have said they will no longer negotiate with the government, said on Tuesday that they might be willing to talk to a third party to mediate between them and the government.
Troops had earlier set up razor-wire barricades across the major Silom Road thoroughfare in the financial district, patrolling streets, taking positions on rooftops and guarding bank buildings.
Demonstrators had braced for battle by stockpiling paving stones and rudimentary weapons, including long, sharpened bamboo poles.
Nattawut, the protest leader, said he was "worried about the force allocation pattern" of the military.
"It looks greater than necessary for just guarding the Silom area," he said. "They are making it into a killing field."
The red shirts, formally known as the United Front for Democracy against Dictatorship, are supporters of Thaksin Shinawatra, the former prime minister ousted in a military coup in 2006.
|Red shirt protesters want the Thai PM to resign and call fresh elections [EPA]
They have demanded that Abhisit Vejjajiva step down, dissolve parliament and call new elections.
But Abhisit, speaking on government-run television channels late on Monday, again rejected those demands.
"If we allow those who use force to threaten a political change, we will have a lawless country," he said. "The priority task of the government is to deal with this group of illegal armed men."
However, the prime minister said he would not set a date for protesters to leave their encampment and promised that the government "will do our duty to respond to legitimate demands from the protesters".
"Let's not draw a deadline [to remove the red shirts]," he said.
"I do realise Thais are troubled, that everyone wants it to be quick ... But there are many factors they have to take into account."
Abhisit's comments appeared aimed at the so-called "yellow shirt" movement, which said on Sunday that they would take action themselves and hold a mass rally unless the government "strictly and efficiently enforces the law" to deal with the crisis.
Yellow shirts' threat
The yellow shirts, representing royalists, the business elite, aristocrats and urban middle class and led by People's Alliance for Democracy (PAD), are opposed to Thaksin.
They would not reveal their exact plans should the authorities fail to clear the streets of the red shirts, our correspondent said, but they did not rule out direct confrontation with the Thaksin supporters.
The yellow shirts staged a crippling eight-day blockade of Bangkok's airports in December 2008, which left more than 230,000 tourists stranded, disrupted trade and led to credit rating downgrades for Southeast Asia's second-largest economy.
The siege ended when the then ruling party, aligned with Thaksin, was dissolved for electoral fraud, paving the way for Abhisit to assume office after a parliamentary vote the red shirts say was influenced heavily by the military in a "silent coup".
Analysts say the six-week protest has evolved into a dangerous standoff between the army and a rogue military faction that supports the red shirts and includes retired generals allied with the twice-popularly elected Thaksin, now in self-imposed exile to escape jail for a corruption conviction.
A failed attempt by security forces to flush protesters from a historic district in Bangkok on April 10 erupted into the worst political violence Thailand has seen in 18 years, leaving 25 dead and more than 800 wounded.
The government accuses "terrorists" or the "third hand" - unknown provocateurs - armed with guns and other weapons of orchestrating the violence and says weapons were stolen from the military.