Troops continued to fire high-powered rifles from behind sandbags in the direction of the protest camp they had surrounded in a bid to contain anti-government demonstrators within a roughly square-mile base in downtown Bangkok's Ratchaprasong district.

In response, "Red Shirt" protesters — whose more militant members have wielded firebombs, rocks, homemade rockets and a few guns against the army and police — called on supporters to hang tough, offered to negotiate if the army ended its crackdown, and appealed to the United Nations to help mediate.

"We cannot appeal to any organization in Thailand to provide justice … and safety for us," Sean Boonpracong, a protest spokesman, said at a news conference.

The government on Sunday rejected negotiations that included preconditions after talks last week broke down when protest leaders upped the ante.

Government spokesman Panitan Wattanayagorn said there was no reason the army should withdraw, since "authorities are not using weapons to crack down on civilians," only on "armed terrorists." He also urged Red Shirt protesters who are threatening security forces to "stop their actions immediately."

The Red Shirt occupation since March of one of Bangkok's swankiest areas has been a disruption for businesses and embassies and has interfered with shopping and transportation.

But a heavy downpour Sunday morning allowed both sides to catch their breath for a few hours. Protesters hung wet pants and T-shirts atop the barricades now ringing high-end hotels and shops. Others lined up for showers in makeshift facilities set up in front of a shopping mall.

The protesters, mostly poor farmers or workers who have adopted the color red as a virtual uniform, are demanding that Prime Minister Abhisit Vejjajiva resign immediately, dissolve parliament and call new elections. They say the government is illegitimate, that it came to power by manipulating the courts and cozying up to the military, and that it embodies an elite indifferent to the plight of the poor.

Analysts said indications were that hard-liners had gained the upper hand within the government, and the army was ready to storm the protest area soon. Authorities had cut off power, water, food and some cellphone coverage to the area and warned protesters to disperse, with Monday declared a school holiday.

The siege is "slow but sure," said Paul Chambers, a research fellow at Germany's Heidelberg University. "It seems the government has now gotten the green light to go in."

Authorities also appeared intent on blocking any financial support the protesters might have been receiving from former Prime Minister Thaksin Shinawatra, a telecommunications tycoon ousted by the army in 2006.

Thailand's National Security Council said it was monitoring 106 bank or stock accounts held by Thaksin's family members and business associates. If any were being used to fund protesters, they would be frozen, warned Thawil Pliensri, the council's secretary-general, adding that banks and other financial institutions had been barred from making any such transfers.

Officials on Sunday also urged the International Committee of the Red Cross and other civic groups to assist protesters willing to leave. Col. Sansern Kaewkamnerd, a national emergency spokesman, said in a televised address that those who left would not face charges.

Some protesters appeared to take the advice. Dozens of tents standing under the elevated railway tracks Saturday had been packed up.

"I'm tired, I feel like I haven't slept for two months," said Wassana Kongkhogkua, 58, a papaya-salad seller from the northern city of Chiang Mai who had been in the protest camp since March.

"I want to go home," she said, adding that she still supported the cause and would consider returning soon.

Analysts said protest leaders might escape the cordon and start demonstrations outside Bangkok, a concern the government apparently shared: Emergency rule was extended Sunday to five more of Thailand's 76 provinces, bringing the total to 23.

A core of Red Shirt supporters in the protest area remained defiant. Hundreds sat on plastic mats before a stage Sunday as speakers urged them to maintain their resolve.

"I will be here until everything is fair and equal, and there are no double standards," said Walangkana Tina, 48. "We are not just sitting in air-conditioned rooms. We are sleeping in the middle of the sun and the rain.

"The government is not listening to us. If they were, this would be finished already."

my-thuan.tran@latimes.com

mark.magnier@latimes.com

Tran reported from Bangkok, Thailand, and Magnier from New Delhi.