Authorities beefed up security in parts of the capital and other areas popular with tourists after the United States and Israel warned on Friday of a possible terrorist attack.
Police detained a Lebanese man reportedly carrying a Swedish passport. Officials said he had links with Hezbollah, a Shiite Islamist group in Lebanon backed by Syria and Iran that is on the US blacklist of foreign terrorist organizations.
National police chief Priewpan Damapong told reporters the suspect, named as Atris Hussein, had given police an address where bomb-making material was being kept.
Officers discovered large amount of substances that could be used to make explosives in a building in Samut Sakhon, southwest of Bangkok, including 4,380 kg of urea and 10 gallons of liquid ammonium nitrate.
Priewpan said the suspect maintained that his group had not planned an attack in Thailand but intended to transport the substances to a third country. The officer declined to give the destination.
Asked about the discovery, Prime Minister Yingluck Shinawatra told reporters: “I have been informed. I would like to ask people not to panic. We are currently in control of the situation.”
Defense Minister Yuthasak Sasiprapha told reporters in the northern city of Chiang Mai on Sunday that Thailand was not the target, although officials have also said that areas of Bangkok frequented by Westerners and Israelis could be hit.
Yuthasak said that a second suspect had managed to leave the country. Police said the detained suspect had not yet been charged with any offense.
Thai officials have seemed irritated by travel adviseries issued by the US and Israeli governments, followed by several more since Friday, and Foreign Minister Surapong Towijakchaikul said diplomats from countries that had issued warnings would meet with him for an explanation on Monday.
Tourism is a big money-earner for Thailand and ministers are keen not to deter travelers, especially after the hit to tourism from severe flooding in 2011 and political unrest in 2010.
