Thai police used tear gas and water cannon against protesters marching on a military base in Bangkok on Sunday to call for King Maha Vajiralongkorn to give up direct command of the army unit housed there.
Protesters threw bottles at police and marched right up to a barricade of shipping containers and barbed wire at the entrance to the base of the 1st Infantry Regiment in Bangkok, one of several army units that government of Prime Minister Prayuth Chan-ocha transferred to the king's control in 2019.
The Thai youth-led political movement rose up last year to demand Prayuth's resignation and broke taboos by calling for reforms of the monarchy.
Protesters also showed support for anti-coup demonstrations in Myanmar, which has been in chaos since the army seized power and detained elected government leader Aung San Suu Kyi.
"Prayuth welcoming a Myanmar official from their military government to Thailand earlier this week also show that he is supporting the dictator there," Chukiat Sangwong, a Thai protest leader told Reuters, referring to Prayuth
"This is not ok with the Myanmar people, so they have joined us here," he said.
Public criticism of the king is illegal in Thailand, with insults to the monarchy punishable by up to 15 years in prison under the country's strict lese majeste law.
The Royal Palace has made no comment since protests began.