Police insists their opertions were based on international standards and the operations came after protesters flouted police warnings.
Meanwhile, protesters announced they would organise a motor rally at the Royal Thai Police Office today.
Redem (Restart Democracy) demonstrators had arranged originally to meet at Democracy Monument at 2pm yesterday, with a plan to march to the Grand Palace.
Redem has no official leaders but still has guards. Created by the Free Youth group in February, it consists of various pro-democracy groups that share common goals at any given time.
The group was looking to push three demands - Gen Prayut Chan-o-cha must resign as prime minister, the budgets for the palace and armed forces must be cut and allocated to COVID-19 relief efforts, and the “tycoon” COVID-19 vaccine must be changed to the mRNA type.
Pol Col Kritsana Pattanacharoen, deputy spokesman of the Royal Thai Police Office, said police deployed rubber bullets and tear gas to stop protesters from advancing.
The demonstrators did not retreat and threw objects including ping-pong bombs at officers, he said, adding the police operation was aimed at keeping order, not making arrests.
A few hundred people arrived at the Democracy Monument around noon. Police closed the area to traffic at 12:20pm and told them to disperse. In front of the Grand Palace nearby, the usual wall of containers was seen, fortified this time with decommissioned tanker cars obtained from the State Railway of Thailand.
At 1pm, police started clearing the area. Rubber bullets were used and at least two people were arrested.
The demonstrators were pushed back to the Phan Fa Bridge. Some threw firecrackers and fired objects with catapults at police.
As the demonstrators arrived at Victory Monument and were heading for Vibhavadi Road, which leads to the army base, police blocked traffic using stacked containers and barbed wire, with crowd control police lining up behind the barriers.
Police told them to go back to Victory Monument. As some of the protesters tried to remove the containers, several tear gas canisters were fired at them at Din Daeng intersection at 3:30pm.
At 5:30pm, police pushed them further back to Victory Monument using a water cannon.
Video taken at the scene also showed tear gas and muzzle flashes - possibly from the firing of rubber bullets - being used by officers positioned on the skywalk overlooking the roundabout. They announced they would dissolve the rally at 8pm.