
The Foreign Correspondents' Club of Thailand (FCCT) had planned to host a panel discussion on the royal defamation law on Wednesday evening.
In a statement the FCCT said police had informed it that soldiers would blockade the building housing the club if the event went ahead.
"The FCCT has now been told that if the event goes ahead, the military will come and seal off access to the Maneeya Centre, where the club is located," it said.
The statement said police had conveyed the message on behalf of the National Council for the Restoration of Peace and Order, the official title of Thailand's junta.
Calls to a junta spokesman by AFP went unanswered Monday.
The move comes less than two weeks after the military forbade a group of lawyers from holding a discussion at the FCCT exploring rights abuses under the military rulers.
"We believe the law is a legitimate subject for discussion, not only for Thais, but also for foreigners who live or invest in Thailand," the FCCT said. "Our discussion would, we believe, have been constructive."