Protesters were set to rally in Bangkok Sunday against the government as tensions rose in the kingdom after the arrest of three activists leading the pro-democracy movement.
Thailand has seen near-daily demonstrations for the past month by student-led groups denouncing Premier Prayut Chan-O-Cha -- a former military chief who led the 2014 coup -- and his pro-establishment administration.
Prominent student leader Parit Chiwarak, bailed a day after his arrest Friday night, vowed to attend Sunday's rally at Bangkok's Democracy Monument.
"We will not disappoint you," he told a crowd of supporters outside the police station after he was released.
Organisers expect thousands to participate. Hundreds of police personnel were seen at the venue before the scheduled start of the protest.
The protesters, partly inspired by the Hong Kong democracy movement, claim to be leaderless, and have relied mostly on social media campaigns to draw support across the country.