Protesters camped out along Ratchadamnoen Avenue said several were injured when someone tossed a canister of tear gas into their location.
Nasser Yeema, an anti-government protest guard, said unknown assailants lit fireworks near the Government House, and 20 minutes later tear gas was thrown at the protesters, most whom had traveled from other provinces to join the protests.
Police said they were not responsible for the use of the tear gas, and no trace of a canister was found at the scene.
The protesters relocated their encampment to Phitsanulok Road, Khaosod reported.
