Bangkok is currently hosting a meeting of foreign ministers from the Association of Southeast Asian Nations (ASEAN) and their counterparts from world powers including the United States, China and Russia.
An agreement would likely sink the opposition Democratic Front coalition's bid to keep members of the junta from retaining dominance over the government five years after the army seized power in a coup.
Activists had planned to hold a news conference at the Maneeya Center in Bangkok - home to the Foreign Correspondents' Club of Thailand (FCCT) - to call on the junta to keep its promise of an election this year, but police issued a warning that stopped the event from going ahead.
Eight people, including three children, were killed by gunmen in Thailand's Krabi province, police said on Tuesday, a mass slaying investigators believe was sparked by a personal conflict. The gang took ten people hostage.