Police said the heroin seized yesterday night in the Andaman Sea port city of Ranong had a street value that would have been USD 96 million.
Thai deputy police chief Maj Gen Somyot Pumpanmuang said today that two men, a Thai and a Malaysian were arrested on trafficking charges when police seized the heroin.
Thai drug seizures for all 2012 totaled 127.5 kg, according to the UN Office on Drugs and Crime. Total seizures for 2009 and for 2010 were also smaller than the latest seizure.
He said police believed the heroin originated in Myanmar and had been smuggled across Thailand's northern border.
Myanmar is the second biggest producer after Afghanistan of opium, from which heroin is derived. According to the UN Office on Drugs and Crime, most heroin made in Myanmar is trafficked to China.