
Thailand’s military has severely restricted public gatherings since seizing power in a coup last May. Taking a hard line on dissent, it has detained more than 300 people, including activists, journalists and politicians.
The leader of a group of four people, Akkarakit Noonchan, was dragged away by plainclothes officers shortly after the beginning of the event at Bangkok's downtown Victory Monument, according to a witness.
Akkarakit said the event, orchestrated by a group calling itself Serichon Thailand 58, was not intended as a protest.
At least two other people were seen being detained. They had earlier displayed T-shirts depicting a bird with its beak and claws bound, as dozens of uniformed police stood by.