The Food and Drug Administration has banned imports of Japanese sweet potatoes after a shipment was found to be contaminated with a radioactive substance.
FDA chief Pipat Yingseri said the contamination was found in a 75-kilogramme batch of sweet potatoes imported from Ibaraki prefecture and tested by the Office of Atoms for Peace (OAP) on Thursday.
The finding was reported on Friday to the FDA, which prompted an import ban on the product, he said.
Parts of Ibaraki are among areas designated by the Japanese government as no-go zones following a series of explosions at a nuclear power plant complex in Fukushima prefecture.
The nuclear complex was damaged by the March 11 earthquake and a tsunami and the explosions caused a radioactivity leak.
Mr Pipat said the sweet potatoes were found to contain Iodine-131, also known as radioiodine.
Public Health Minister Jurin Laksanavisit said the sweet potatoes contained 15.25 becquerels per kilogramme (Bq/kg) of Iodine-131.
Radioiodine has a half-life decay of about eight days. Although the contamination amount was still under the harmful level set by the World Health Organisation at 100 Bq/kg, the potatoes would be destroyed, he said.
Mr Jurin said the contaminated potatoes were imported to Thailand and were among 94 samples of food imports from Japan tested by the OAP.
The Science and Technology Ministry reported to the cabinet that the OAP was also monitoring radiation levels in tap and sea water in Thailand but has not detected any harmful levels, acting government spokesman Panitan Wattanayagorn said.
Mr Panitan said the Energy Ministry has agreed to send two sets of diesel-fuelled turbines to Japan to help ease the electricity shortage there.