Ghanavatirajabnejad Keyvan, 33, was detained at Suvarnabhumi airport late Tuesday as he walked through the nothing-to-declare channel after arriving on an Emirates flight from Dubai, they said.
Customs anti-narcotics officials found a bag of pure methamphetamine, commonly known as ice, concealed in a special compartment of his luggage, they said.
The drug has a street value of 17 million baht (more than $500,000).
The Iranian national was charged with smuggling illicit drugs and possession of drugs with intent to supply, both of which carry the death penalty in Thailand, officials said.
Senior customs department official Worapat Chaovisit said Keyvan refused to answer questions, saying he did not understand English and needed an interpreter.
In the past year customs officials at Suvarnbhumi have arrested 31 people smuggling a total of 52 kilos of drugs including heroin, methamphetamine, cocaine, ecstasy and hashish, the customs department said.
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