The decree invoked by the caretaker government to control anti-government protests has already hurt the tourism industry.
"The fate of international events that were to be held in Thailand during the third and fourth quarters is uncertain,'' said Nopparat Maythaveekulchai, president of the Thailand Convention and Exhibition Bureau.
He said organisers of international events usually take 3-6 months to prepare an event, but the 60-day emergency decree, enforced since Jan 22, will likely disrupt their plans.
Normally, Thailand hosts big Mice events in the second half of the year, and Mr Nopparat is worried that some may be postponed or switched to other countries if the government insists on keeping the emergency decree for that long.
The law, which prohibits political gatherings and activities in Bangkok and parts of Nonthaburi, Pathum Thani and Samut Prakan provinces, is worrying foreign businessmen.
The organiser of Apricot 2014, an international internet service forum, decided to switch from Thailand to Petaling Jaya, Malaysia due to the political turmoil. The forum will be held from Feb 18-28.
"I'd like to suggest the government revoke the decree as soon as possible to keep the projection on track," Mr Nopparat said.
Thailand this year expects to attract 987,000 Mice travellers from abroad providing revenue of 96.9 billion baht, up by 5% and 10% from last year, respectively.
Kasikorn Research Center says prolonged political unrest will bring down revenue from the tourism industry by at least 50 billion baht, and the number of foreign tourist arrivals may miss the projection by 1 million.
In a better scenario, with the political unrest ending in the first quarter, the research house believes Thailand may lose 500,000 foreign visitors and 20 billion baht.