Between 2007 to 2013 Thailand had lost export markets worth about 180 billion baht to other Asean members. During that period it also signed a trade agreement under the Asean+3 grouping that includes China, South Korea and Japan, Mr Aat said on Thursday.
The lost markets included rubber, automobiles, auto parts, transport equipment, wooden products, electrical appliances, rice, palm oil and garments - industries that make up about 50% of Thailand's exports.
Thailand is losing competitiveness in the export of rice, raw palm oil and garments, Mr Aat said.
If its political problems continue until late this year, Thailand would lose competitiveness in the export of wooden and electrical products and the value of its export losses to other Asean members could rise to 250 billion baht, Mr Aat said. At present, its wooden and electrical products have medium competitiveness.
If the political problems continue, 700,000-800,000 of the roughly 2 million small and medium enterprises in Thailand (30-40%) would collapse, he predicted. This declining competitiveness would be compounded after the formation of the Asean Economic Community, he warned.
Mr Aat said he expected Thailand's gross domestic product growth to fall this year and next year as a result of the 2015 national budget being delayed.