The value of exports fell 0.95% year-on-year in November to US$21.24 billion on the China-United States trade war and lower supply-chain exports to China, resulting in a $1.17 billion trade deficit.
Announcing the figures on Friday, the Commerce Ministry also reported that imports increased by 14.66% to $22.41 billion last month.
In the first 11 months of 2018, exports expanded by 7.29% to $232.72 billion, imports rose by 14.77% to $231.34. The country posted a trade surplus of $1.38 billion in the January-November period.
Pimchanok Vonkorpon, director-general of the Commerce Ministry's Trade Policy and Strategy Office, said November's exports dropped because of a high base in the same period last year and the indirect impacts of the trade war on Thailand, which is part of the supply chain.
However, she said, last month's exports grew steadily in important markets like Japan (up by 4.3%), the US (11.9%), Cambodia, Laos, Myanmar and Vietnam (CLMV - up by 17.6%). The value at these markets was higher than that of exports to China and the US. It showed that Thailand was depending more on regional markets.
Exports to India rose by 3.6%, those to the Commonwealth of Independent States 6.6% and those to Switzerland 52.5% on rising gold prices.
Exports to China dropped by 8.9%. The were also declines in exports destined for the European Union (2.0%), other Asean nations (4.3%), South Asia (7.6%), Hong Kong (1.1%), South Korea (1.8%), Taiwan (3.0%), the Middle East (17.4%), Australia (11.8%), Africa (9.8%) and Latin America (9.7%).
Ms Pimchanok said the Commerce Ministry still hoped exports would rise by 8% throughout this year, as was earlier expected.
She warned that exports to Europe would face higher competition due to a free trade agreement between the European Union and Vietnam that would take effect early next year.