Suthep Thaugsuban said the meeting with Prime Minister Yingluck Shinawatra was held under the auspices of the military, which says it is neutral in the conflict. His account of defiance drew lusty cheers from his supporters.
Police throughout the day fought off mobs of rock-throwing protesters who tried to battle their way into the government's heavily fortified headquarters and other offices. Mobs also besieged several television stations, demanding they broadcast the protesters' views and not the government's. Several of the capital's biggest shopping malls closed in the heart of the city due to the unrest.
With skirmishes around Yingluck's office at Government House continuing as darkness fell, the government advised Bangkok residents to stay indoors overnight for their safety.
The protests have renewed fears of prolonged instability in one of Southeast Asia's biggest economies. Sunday marked the first time police have used force since demonstrations began in earnest a week ago - a risky strategy that many fear could trigger more bloodshed.
At least three people were killed and 103 injured in skirmishes over the weekend, according to police and the state's emergency medical services. The deaths occurred at a Bangkok stadium where the body of one protester shot in the chest lay face-up on the ground. The death toll was revised from four after the emergency services office said there had been a mix-up in information from hospitals.
Suthep insisted to his supporters that the meeting with Yingluck did not constitute negotiations. The protesters had dubbed Sunday "victory day" but failed to attain their main stated goal of taking over the prime minister's offices, despite engaging in pitched street battles. Yingluck's government has gone to painstaking lengths to avoid using deadly force.
"I only came to tell Ms. Yingluck Shinawatra that right now, people all over Thailand have stood up to show their ownership of Thailand," Suthep said.
He told followers it would take another two days for their goal to be reached. He earlier called for all public servants to take Monday off. Last week, protesters tried to disrupt government operations by besieging and occupying parts of several ministries and other government offices.
"If Prime Minister Yingluck Shinawatra listens to the people's voices and returns the power to the people, we will treat Prime Minister Yingluck Shinawatra with politeness because we all are good citizens," he said.
Spokesmen for both the prime minister and the army said they were too junior to comment on any meeting. Government spokesman Teerat Ratanasevi said Yingluck was not expected to make a statement Sunday night. She did not appear in public, and her aides said she was in a safe place.
While the talks between the main protagonists suggest a faint possibility of a peaceful settlement, they also underline the traditional powerbroker role of the military, which could tumble the government even without a coup by refusing to let its forces help keep the peace. More than 2,500 military personnel were deployed Sunday in support of police defense efforts.
Political instability has plagued Thailand since the military ousted Yingluck's brother, Thaksin Shinawatra, in a 2006 coup. Two years later, anti-Thaksin demonstrators occupied Bangkok's two airports for a week after taking over the prime minister's office for three months, and in 2010 pro-Thaksin protesters occupied downtown Bangkok for weeks in a standoff that ended with parts of the city in flames and more than 90 dead.
Any further deterioration is likely to scare away investors as well as tourists who come to Thailand by the millions and contribute 10 percent to the $602 billion economy, Southeast Asia's second largest after Indonesia. It is also likely to undermine Thailand's democracy, which had built up in fits and starts interrupted by coups.
The latest unrest began last month after an ill-advised bid by Yingluck's ruling Pheu Thai party to push an amnesty law through Parliament that would have allowed the return of her self-exiled brother, who was overthrown after being accused of corruption and abuse of power. Thaksin lives in Dubai to avoid a two-year jail term for a corruption conviction he says was politically motivated.The bill failed to pass the upper house of parliament, emboldening protesters, who drew 100,000 people to a mass rally in Bangkok one week ago. Then, over the past week, they seized the Finance Ministry, camped at a sprawling government office complex, cut power to the national police headquarters and briefly broken into the army headquarters compound to urge the military to support them.
The demonstrators want to replace Yingluck's popularly elected government with an unelected "people's council," but they have been vague about what that means. Because Yingluck's party has overwhelming electoral support from the country's rural majority, which benefited from Thaksin's populist programs, the protesters want to change the country's political system to a less democratic one where the educated and well-connected would have a greater say than directly elected lawmakers.
Some of Sunday's most dramatic scenes played out in front of Government House, where more than 1,000 protesters wearing bandanas and plastic bags over their heads hurled stones, bottles and sticks at police, who fought back with rubber bullets, water cannons and tear gas over barricades that separated them. Protesters clipped away at coils of barbed wire that surrounded the compound, pushed over barriers and at one point tried to drag one away with a green rope tied to a truck.
A few miles away, police drove back another crowd of protesters at the city's police headquarters.
Until this weekend, the demonstrations were largely peaceful. But Saturday night, rival groups clashed in northeastern Bangkok, where a large pro-government rally was being held in a stadium. Dozens were wounded, and unidentified gunmen were also responsible for the three shooting deaths.
Army commander Gen. Prayuth Chan-ocha - who said last week the army would not take sides - urged the police not to use force and also called on protesters to avert violence, according to Lt. Col. Winthai Suvaree, an army spokesman.
Most of the protesters are middle-class Bangkok residents who have been part of the anti-Thaksin movement for several years and people brought in from the opposition Democrat Party strongholds in the southern provinces.