HONG KONG — Officials in Thailand on Wednesday prevented an international rights group from publicly presenting a report that accuses the ruling military junta of torture and abuse, the group said.

Minutes before the briefing was scheduled to start at a hotel in Bangkok, the Thai capital, plainclothes police officers warned that two employees of the group, Amnesty International, would breach Thai labor law if they spoke publicly, according to one of the employees, Yuval Ginbar. Amnesty canceled the briefing.

Mr. Ginbar said it was not clear how he and his colleague, who have British and Indonesian passports, respectively, would have been in violation of the law. Both had business visas and assumed they were in compliance with the government’s labor regulations, Mr. Ginbar said.

“I think it’s a facade for trying to shut us up,” Mr. Ginbar said of the police officers’ warning. He added that a United Nations official had also been scheduled to speak.