BANGKOK (Reuters) - Thousands of protesters began a march to the office of Thai Prime Minister Thaksin Shinawatra on Tuesday, vowing to surround it until he quits.
The march, billed as the final showdown by the extra-parliamentary coalition organising the campaign to bring down Thaksin, began after an all-night rally next to Bangkok's Grand Palace which was attended by around 40,000 people.
Many of them stayed all night and began marching under a watchful police presence after a powerful indirect appeal from revered King Bhumibol Adulyadej not to allow the protest to descend into violence, as other have in the past.
Large numbers of police were at Government House, where the cabinet was due to meet at 8.30 a.m. (0130 GMT).
Chamlong Srimuang, the ascetic general who led a 1992 "people power" uprising against a military government in which about 50 people were killed, said there would be no trouble this time.
"We will march peacefully," he told the rally, to chants of 'Thaksin, get out'. "You can be assured that nothing will happen. Do not be afraid."
His blue-clad "Dharma Army", or the Army of Buddha's Teachings -- barefoot and carrying the red, white and blue Thai flag -- led the way out of the rally ground to Government House about 5 km (3 miles) away.
Thaksin, who called snap elections on April 2 to defuse a campaign fuelled by the tax-free $1.9 billion sale by relatives of the business empire he founded, would not be at the cabinet meeting. He was to chair it by video-link from the provinces.
Previous rallies by the People's Alliance for Democracy, an extra-parliamentary coalition which accuses Thaksin of corruption and abuse of power, have been peaceful, even festive.
But 6,000 Thaksin supporters headed from northern Thailand to Bangkok in tractors and trucks, fanning fears that yet again a Thai political confrontation could turn into street violence.
Such fears clearly penetrated the royal palace, and led to the screening on all six Thai television channels on Sunday of footage of the King, a constitutional monarch, talking in 1992 to the then prime minister and Chamlong as they knelt before him.
Suchinda Kraprayoon, then head of a military-led government, quit after the audience and peace returned to Bangkok's streets.
Officials say that should Tuesday's protest turn violent, the government would declare a state of emergency, which could bring troops onto the streets of a country with a long and relatively recent history of military intervention.
Military chiefs have been going out of their way over the past few weeks to stress that they have no intention of intervening and that the era of coups is over.
The anti-government campaign took off in late January when the tax-free sale of the telecoms business empire Thaksin founded outraged Bangkok's middle classes.
Thaksin hit back against what he calls "mob rule" by calling elections three years early and accusing the three main opposition parties of betraying democracy by boycotting the polls.
But the People's Alliance for Democracy, adamant Thaksin must go, and the government, adamant he must stay, appeared to be on a collision course.
(Additional reporting by Pracha Hariraksapitak and Nopporn Wong-Anan)