BANGKOK -- After occasional skirmishes in recent months, yellow-shirted royalists clashed openly on Tuesday afternoon with pro-democracy protesters who had breached a razor wire barricade outside parliament, taking them to within 30 meters of the compound.
The two groups threw projectiles, including bottles and rocks, and one protester was injured when hit over the head with a plank. Police at one point use used water cannons to break the feuding groups apart.
The Yellow Shirts on the streets Tuesday were the remnants of an earlier protest that began at 9:30 a.m. opposing any amendments to the constitution. Mostly in their thirties and forties, they had been kept separate from the pro-democracy protesters, and were not subject to any of the initial police actions.
Inside the parliament building, lawmakers continued with a sitting to review proposed amendments to Thailand's 20th constitution since 1932, which was approved by national referendum in 2016 and promulgated the following year.
Five proposals have been made by opposition parties and one by Palang Pracharat, the main party in the ruling coalition. A more radical seventh proposal from iLaw, a legal activist group, included adjustments to the first two chapters, which cover the monarchy.
At about 4 p.m., police began evacuating parliamentarians who wished to leave through the rear exit using a pier on the Chao Phraya river, and they left by boat. Some opposition lawmakers also emerged out front to discuss with police ways of defusing the confrontation.
Police first opened up with water cannons and tear gas at 2:30 p.m. The water barrages continued throughout the afternoon -- eight times by 4:50 p.m. The water was laced with skin irritants and bright dyes, including purple. A Western journalist said the chemical used caused a strong burning sensation that began to dissipate after about five minutes.
Police Col. Krissana Pattanacharoen, deputy spokesman of the Royal Thai Police, said the authorities warned protesters to remain 50 meters from the parliamentary compound. During the afternoon, police announced that rubber bullets could be used, and officers were visible carrying dedicated riot guns.
"As you can see, steps have been taken very carefully but then things escalated," Krissana told reporters. "What we need to do is bring this back to negotiations." He insisted that the authorities are following standard riot control procedures by warning protesters over public address systems, and using clean water initially. Water laced with chemical irritants and strong dyes come later.
Krissana confirmed that firing rubber bullets remains an option. "If there's a reason to do so, we would," he said.
Police said that at least five protesters were injured by tear gas, and had been taken to hospital.
As dusk approached, more protesters were arriving in response to rallying posts on social media.
"Everybody please come to Parliament House and be ready," Free Youth group said in the banner posted on Twitter.
Leaders of the protesters announced the end of the rally at around 9 p.m., calling for another gathering on Wednesday at Ratchaprasong intersection located at the heart of a key business and retail area.