Police hauled four Myanmar nationals from a sedan they stopped on a street in Samut Prakan and seized 100 bars of heroin found in the car on Friday.
Earlier on Friday, in Nakhon Ratchasima, three Thai men were caught with 270 kilogrammes of marijuana.
Drug suppression police arrested Napavorn Phitpheng, 34, Surin Chan-on, 29, and Jirayu Ounpaisarnwong, 37.
Nine packages containing 270 kilogrammes of compressed marijuana were found n the suspects’ two vehicles at a U-turn beneath a bridge at kilometre markers 3-5 on Road 201 in Sikhiu district, Nakhon Ratchasima, Pol Lt Gen Sarayut Sa-nguanphokhai, chief of the Narcotics Suppression Bureau, said.
The arrest followed a tip about a drug delivery from Laos to the Central Plains area. (continues below)
In Samut Prakarn, NSB police assisted by US Drug Enforcement Administration officers arrested four Myanmar suspects, two men and two women.
They were pulled from their car after it was stopped in the middle of Soi Sukhumvit 109 in tambon Samrong Nua of Muang district.
Police said 100 bars of heroin, weighing 37.5 kilogrammes in total, were found in the vehicle.
The suspects were identifed as Win Win Mong, 51; Tey Mong San, 46; Tan Gee, 44; and Thian Than, 43, but no spellings were given for their names.
During questioning, the four allegedly told police they had been in Thailand for 4 or 5 years. They had recently been contacted by a man in Myanmar and asked to smuggle heroin for sale in areas near Bangkok.
The suspects were held in NSB custody for legal action. Investigators were extending the investigation.