Police estimated the crowd at 2,000, although organisers said 3,000 protesters were at the rally, outside Bangkok's municipal centre, calling on the junta to step down.

"I am really against any government that resulted from an undemocratic system, because it is not right to take power by force," said one 52-year-old protester, who asked only to be identified as Yod.

"If the junta tries to use their power to prevent people from coming to the protest, people defy them," he said.

Security forces were hardly visible, staying largely on the sidelines of the protest, one of the largest since the military-backed coup that ousted prime minister Thaksin Shinawatra in September last year.