Four police officers appeared at the Progressive Movement office on Friday afternoon with a search warrant, interrupting a press conference called by Piyabutr Saengkanokkul.
The police, from Makkasan station, walked into the press conference room at the Thai Summit building, armed with a search warrant issued under the state of emergency.
At the time, Mr Piyabutr was at the podium speaking against the state of emergency and legal action taken against protesters accused of causing harm to Her Majesty the Queen.
"I am here to check on law and order within my jurisdiction," a police officer said.
The search at the Progressive Movement premises was the first since the emergency decree was issued in Bangkok about 4am on Thursday.
The police officer walked out of the press conference room, and then returned to talk with Mr Piyabutr, co-founder of the political movement. Their talk was continuing.
Mr Piyabutr urged the police officers to stay with the people, instead of following orders from their superiors.
The emergency decree, formally approved by the cabinet on Friday, bans meetings of more than four people and gives authorities power to ban any action deemed to be causing a public disturbance.
