Thousands of anti-government protesters rallied in central Bangkok today, the start of what they call the "final battle" in a five-month street campaign to oust the administration.
The crowd led by the People's Alliance for Democracy (PAD) planned to march to parliament early tomorrow, where police have erected barricades and stationed trucks with water cannons.
A similar protest in October left two people dead and hundreds wounded, including scores of police, when police fired tear gas to break up the rally aimed at disrupting parliament.
This time, police have been ordered not to use tear gas or other "weapons" and only carry shields, government spokesman Nattawut Saikuar said after a meeting of security ministers.
Prime minister Somchai Wongsawat, whom the PAD accuse of being the puppet of exiled former leader Thaksin Shinawatra, his brother-in-law, assigned army chief Anupong Paochinda to monitor the protests while he attends an Asia-Pacific summit in Peru.
Major bloodshed would raise the chances of a military coup only two years after the army's removal of Mr Thaksin, who now lives in exile after skipping bail on corruption charges.
But Mr Anupong, who has put more than 3,000 anti-riot soldiers on standby to help the police, has said a putsch would do nothing to resolve Thailand's fundamental political rifts.
The PAD enjoy the backing of Bangkok's urban middle classes and elite, including Queen Sirikit, while Mr Thaksin and the government claim their support from the rural voters that returned a pro-Thaksin party in a December election.
The PAD is calling the march "its final battle" to oust the government, which it blames for a grenade attack last week that killed one person and wounded 23. Another grenade blast near their protest site wounded eight PAD security guards yesterday.
Mr Somchai has denied the government or its supporters are behind the blasts. Police have made no arrests so far.
On the outskirts of Bangkok, thousands of red-shirted government supporters rallied in a Buddhist temple today to show their support for Mr Somchai.
Jatuporn Prompan, a leader of the United Front of Democracy against Dictatorship (UDD), said they would not march on parliament tomorrow to confront the PAD.
Raising the pressure on Mr Somchai, public sector unions have called a nationwide strike for Tuesday unless he stands aside, a threat that, if carried out, would deepen the economic impact of a political crisis now in its fourth year.
Government decision-making has ground to a halt, intensifying fears about the export-driven economy's ability to withstand a global recession. Some foreign firms are already cutting back.
Reuters