Story highlights Laying siege to Government House would be a symbolic victory

Three people were killed in clashes Saturday

Demonstrators want the army to help oust the Prime Minister

The leader of anti-government demonstrations in Thailand on Sunday urged Yingluck Shinawatra to resign, the latest move in a relentless campaign to oust the prime minister.

Protest leader Suthep Thaugsuban, a former deputy prime minister under the previous Democrat-led government, gave Yingluck two days to "return power to the people unconditionally," Suthep's group said.

The face-to-face meeting came the same day protesters tried to force their way into the government headquarters and a police club compound, hoping to find Yingluck. Police fired tear gas to disperse them.

"The most violently active areas are around the Government House," said Lt. Gen. Paradon Pattanathabut, referring to the government headquarters.

The prime minister was not at the police club compound as she was rumored to be when demonstrators stormed the building.

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The state television station, Thai Public Broadcasting Service, continued with its regular programming. But officials there were in negotiations with the protesters, said to number in the hundreds, said government spokesman Teerat Rattanasevi.

Laying siege to Government House would be a symbolic victory for the demonstrators. It's the seat of power.

Yingluck moved her offices to another location when the unrest bubbled over.

Undeterred, protesters -- with handkerchiefs covering their noses and mouths to ward off the sting of tear gas -- threw rocks across the fence that rings Government House toward the phalanx of riot police on the other side.

In response, police lobbed tear gas, causing protesters to scurry. A few minutes later, they returned.

So it went for the better part of the day.

Deadly clashes

Yingluck has said authorities will "absolutely not use violence" to disperse the demonstrators. But the situation is delicate after Thai police issued an arrest warrant against Suthep, the protest leader.

On Saturday, three people were killed and more than 60 wounded in clashes between protesters and Yingluck's supporters in the Thai capital, Bangkok.

Each side blamed the other for provoking it. Until Saturday's incident, the monthlong protests had been mostly peaceful and without fatalities.

In recent days, the demonstrators have been seeking out increasingly high-profile targets, such as several government ministries.

"We have spread the message to protesters that we are going to retake the government complex and the ministry of finance back," Paradon said.

On Friday, they jumped over the gate of the army headquarters, demanding the military's help in overthrowing the government.

So far, the army has stayed on the sidelines. But the military intervened in 2006 when it ousted Yingluck's brother -- and then-prime minister Thaksin Shinawatra -- in a bloodless coup.

Yingluck's critics accuse her of being Thaksin's puppet and say she's simply a placeholder for her brother until he can return from self-imposed exile.

In an interview with CNN's Anna Coren on Friday, Yingluck denied those allegations.

Origins of the protests

The protests started as a response to a government-backed amnesty bill that could have extended a pardon to Thaksin and opened the door for his return. Thaksin can't return home now because he risks a two-year prison sentence on a corruption conviction.

The Thai senate rejected the bill on November 11, but opposition demonstrators have called since then for Yingluck's government to be replaced.

Yingluck survived a no-confidence vote in parliament on Thursday. A spokesman for her Pheu Thai Party said she would not resign or dissolve the parliament.

"She will stay in power," Prompong Nopparit said.