The state of emergency was announced after a cabinet meeting on Tuesday and comes after a spate of attacks with explosives and firearms on the anti-government protesters blockading central Bangkok for which the government and the protesters blame each other.
The emergency decree gives authorities the power to impose curfews, detain suspects without court permission, censor media and declare parts of the capital off-limits.
Tourism Council of Thailand president Piyaman Techapaiboon said the decree will dramatically affect tourism, especially group tours and business travellers who have to visit restricted areas in the city. "The emergency decree will affect not only areas under its purview but also other destinations because Suvarnabhumi airport will be controlled by the special law as well," she said.
The U.S. State Department, Taiwan, Australian governments has issued a travel alert for Thailand, warning visitors about demonstrations in Bangkok and surrounding provinces.