Police have arrested more than 20 people under sweeping new emergency measures, with pro-democracy activists reporting a handful of high-profile leaders are among those detained.
Thailand has issued an emergency decree banning protests as it clamps down on largely peaceful pro-democracy rallies that have also targeted the monarchy.
Under the new emergency measures, gatherings of five or more people have been banned, as has the publication of news or online information that “could create fear” or “affect national security”.
Police in Bangkok said they would set up checkpoints coordinated with the army to stop protesters gathering under emergency measures imposed to end three months of anti-government protests.
The arrests came after thousands gathered in Bangkok, including on the route of a royal motorcade, with many raising a defiant three-fingers.
Criticism of the monarchy is punishable by up to 15 years in prison under lese majeste laws, though Prayut said earlier this year the king had asked that they not be enforced for now.