Police fired tear gas and rubber bullets to disperse another anti-government protest in Bangkok on Wednesday.
The demonstration, organised by the Tha Lu Fah group, started at 3pm at Victory Monument.
"Police are not our enemies. Our true enemy is the government," one protester told the rally.
Hundreds of protesters threw paint at a line of riot police who confronted them as they tried to march to the residence of Prime Minister Prayut Chan-o-cha at the 1st Infantry Regiment on Vibhavadi Rangsit Road.
Police responded with tear gas and rubber bullets to disperse them. Protesters retaliated by flinging projectiles and setting a police tow truck on fire, sending black smoke pluming into the air.
About a dozen demonstrators were arrested.
The rally was called off at about 4pm, but some protesters decided to move to a nearby area in Din Daeng, the scene of a violent clash with police on Tuesday night.
Police blocked the route to the prime minister's house with shipping containers and razor wire. But sporadic clashes continued into the evening, with police deploying water cannon.
- Officers injured -
Eight officers were injured, mainly by protesters throwing fireworks, police said, adding that they had made 13 arrests.
"The protesters repeatedly attacked police by throwing firecrackers, ping pong bombs, and (using) slingshots," Royal Thai Police deputy spokesman Kissana Phathanacharoen told reporters.
It was the second anti-government rally in two days in Bangkok.
The Metropolitan Police Bureau said on Wednesday that 48 protesters had been arrested on Tuesday and 122 motorcycles seized, and more arrests would follow.