Thailand warns of emergency

By mid-evening police estimated some 30,000 people had streamed into a field near the royal palace for the fifth rally in as many weeks. The demonstrators plan to camp overnight and then march on Thaksin's office early Tuesday.

Thaksin's supporters, meanwhile, were marching from the countryside to show their strength in the capital, raising fears of violent confrontations.

"If they destroy state property or burn government buildings, we will announce a state of emergency, beginning by imposing a curfew," a senior official at the National Intelligence Agency said of Monday's protest.

"If the situation grows too severe for government officials to control it, the authorities will be authorised to arrest protest leaders," he said on condition of anonymity.

Thaksin said intelligence reports indicated there would be attempts to incite unrest during Tuesday's march on Government House, and he had told police to exercise restraint.

"I have instructed police not to use their weapons in any event," he told some 100,000 supporters at a campaign rally in the rural northeast.