Hundreds of Thai riot police are clearing areas of Bangkok where anti-government protesters have set up camp for weeks.
There were no reports of clashes in the Friday police operations to clear the Government House and other official buildings.
Baton-wielding, helmeted police removed tents and barriers belonging to the protesters, who were warned through loudspeakers not to resist.
Issara Somchai of the opposition People's Democratic Reform Committee suggested many protesters will not back down easily.
"No return. Every place [that's been occupied] will not be given back. If the police want to disperse us, I believe there will be a confrontation," said Issara.
Policemen charge against anti-government protesters at one of their barricades near the Government House, Bangkok, Feb. 18, 2014.
A policeman aims his weapon towards anti-government protesters during clashes near the Government House, Bangkok, Feb. 18, 2014.
Policemen take cover as shots are fired during clashes with anti-government protesters near the Government House in Bangkok, Feb. 18, 2014.
Anti-government protesters lift a police car after clashes with Thai riot police officers, near Government House, Bangkok Feb. 18, 2014.
An anti-government protester takes pictures of shotgun cartridges placed onto a board used to transport wounded people during clashes with police, near the Government House, Bangkok Feb. 18, 2014.
Anti-government protesters celebrate on top of a destroyed police vehicle after clashes near the Government House in Bangkok, Feb. 18, 2014.
A man confronts police officers during an operation to reclaim government offices occupied by anti-government protesters on the outskirts of Bangkok, Feb. 14, 2014.
A man prays as he and colleagues confront police during an operation to reclaim government offices occupied by anti-government protesters on the outskirts of Bangkok, Feb. 14, 2014.
A local journalist is carried away by medics after being wounded from an explosive thrown towards riot police trying to retake a protest site in Bangkok, Feb. 14, 2014.
An anti-government protester sits on the ground praying in front of a line of Thai police near Government House in Bangkok, Feb. 14, 2014.
Anti-government protesters gesture from a barricade where they confront riot policemen near the Government House in central Bangkok, Feb. 14, 2014.
Riot police remove tires and other obstacles as they retake a stretch of a road from anti-government protesters in Bangkok, Feb. 14, 2014.
Police said they are searching the areas for weapons, and accuse many of the protesters of gathering illegally.
Chalerm Yubumrung, who is leading the police operation, told protesters that if they do not leave, the law will be "gently enforced."
Authorities last month announced a state of emergency and have put out arrest warrants for many of the protest leaders.
However, until now, police had largely allowed the demonstrations, which blocked intersections and sometimes occupied government compounds.
The opposition protesters are trying to force Prime Minister Yingluck Shinawatra from power, saying her government is hopelessly corrupt.
Clashes and small-scale attacks on protesters have killed at least 10 people since November, Thailand's worst political violence since 2010.
Yingluck had hoped early elections, held February 2, would help resolve the crisis, which has gripped the country since November, but the opposition Democratic Party boycotted the vote. Many opposition protesters also disrupted voting in several provinces.
The ruling Pheu Thai Party is thought to have won the election, but results cannot be announced until another round of voting is held.