Thai Security Chief claims protesters have not seized state buildings
Earlier, anti-government protest leader Suthep Thaugsuban said in a televised address that protesters had occupied 12 government buildings "peacefully and without weapons".
A total of around 30,000 protesters massed on Sunday at a number of government buildings and tried to storm some. Police fired teargas to repel them. Four people have been killed and at least 57 wounded in the weekend violence.
Thai riot police on Sunday used tear gas and water cannon to prevent protesters from occupying key government sites, raising fears of a prolonged political crisis in Southeast Asia's second-largest economy.
More than 21,000 police and about 1,000 soldiers were deployed in the capital to stop protesters seeking to topple the government of Prime Minister Yingluck Shinawatra from occupying Government House, the cabinet's administrative headquarters, and other installations.
The protesters, mainly supporters of the opposition Democrat Party, accuse Shinawatra of being a stooge of her brother and former prime minister Thaksin Shinawatra, who runs the ruling Pheu Thai Party from exile.
The efforts to seize government offices have been going since a November 24 demonstration drew more than 100,000 people. Protesters have occupied parts of the Finance Ministry and other government buildings.
"We are trying to open a dialogue with them first, because tomorrow will be a working day," said Police Lieutenant Colonel Kissana Phatsanacharoen.
"We haven't given them any deadline for leaving the buildings," he said.
Clashes broke out between protesters and government supporters Saturday night near a sports stadium in eastern Bangkok where an estimated 60,000-strong pro-government protest had taken place.
At least two people died in the melee and many were injured, Kissana said.
The pro-government rally was dispersed by its leaders Sunday morning to ease tensions, he said.
Anti-government protesters planned to block Government House and the ministries of interior, foreign affairs, commerce, education, finance and labour and other targets in a bid to force a work stoppage by Monday.
Protest leader Suthep Thaugsuban urged his supporters in a speech broadcast live on private television to press on with demonstrations until the government stepped down.
Suthep, a former deputy prime minister who resigned from the Democrat Party to lead the protests, urged civil servants not to show up for work on Monday.
The government pledged not to use excessive force against the protesters, employing only crowd control methods such as batons, tear gas and water cannons.
The crisis started on November 1, when the ruling coalition attempted to push through an amnesty in parliament that would have pardoned Thaksin and thousands of other politically related cases during 2004-13.
The amnesty bill was later rejected by the Senate.
Thaksin has been living abroad since 2008 to avoid a two-year jail sentence for abuse of power. He was prime minister between 2001 to 2006, before being ousted by a coup.
"We understand that the protest leaders are trying hard to force the government to use violence in order to increase their support for their own benefit," said deputy prime minister Phongthep Theokanjana.
Bangkok has been the scene of street protests almost annually since 2005. Mass protests resulted in the closure of the capital's two airports in 2008 and bloody street battles left more than 92 dead in 2010.
Two people have been killed and 45 wounded during political violence in the Thai capital, emergency services said Sunday, as the opposition vowed a final push to overthrow the government.
"The confirmed toll is now two dead and 45 injured," an official at the city's Erawan emergency centre told AFP.
The circumstances were unclear but the violence broke out after a confrontation late Saturday between opposition protesters and government supporters staging their own rally at a Bangkok stadium in support of Prime Minister Yingluck Shinawatra.
Voice of Russia, AFP, dpa