Prime Minister Yingluck Shinawatra insisted on Saturday that packed rice is up to international standards and safe for consumption.
She was responding to growing consumer concerns about the use of chemical fumigants and possible health impacts.
Speaking on her "Yingluck Government Meets the People" on NBT, the premier said chemicals were introduced only at the packaging stage.
Ms Yingluck said she had ordered officials from the public health, agriculture and science and technology ministries to conduct detailed inspections at rice packaging plants to restore confidence among local and overseas consumers.
She admitted that reports about possible chemical contamination had made consumers feel uncomfortable, affected rice farmers' incomes and hurt rice exporters.
Rice packagers, she said, must be honest and adhere to ethics in order to maintain the reputation of the country as a global food source and to ensure the safety of consumers, Ms Yingluck said.
Consumer groups have been urging government agencies to reveal details of lab tests to ensure the results were not subject to political interference.
The Food and Drug Administration (FDA) on June 28 said it found no irregularities in 57 packed rice samples it tested. The brands were not mentioned at the time.
However, the Foundation for Consumers (FFC) last Tuesday said its own tests of 34 of 46 packed rice samples contained various amounts of methyl bromide, an odourless, colourless gas used to fumigate rice. Only one, the Co-Co brand, exceeded the international Codex safety limit of 50 parts per million (ppm) at 67.4 ppm.
The FDA subsequently released a new report saying it too had found Co-Co rice over the limit, adding that its first test did not include the brand.
The agency reveals product brands only if they are found unsafe for consumers, said Srinuan Korrakochakorn, the agency's deputy secretary-general.
Almost 200 samples of packed rice have been collected since June 18. Lab tests on 143 have been completed as of Friday, according to the FDA website.