Close to 22,000 "yaba" tablets worth over $540,000 were seized at the Woodlands Checkpoint on Tuesday.
It is the largest single seizure of such tablets since 1999. Four suspects have been arrested in connection with the case, said the Central Narcotics Bureau (CNB) and the Immigration and Checkpoints Authority (ICA) in a joint statement on Wednesday.
At about 7.45pm on Tuesday, ICA officers checked a Thailand- registered car driven by a 51-year-old Thai man.
He was immediately arrested after four black packages were found hidden behind the car's glove compartment. They contained a total of 21,910 "yaba" tablets, also known as methamphetamine. If convicted, the man could face the death penalty.
CNB officers launched two follow- up operations which led to the arrest of two Malaysian men and one Singaporean woman, aged between 35 and 41, in the Jalan Sultan area. They are believed to be connected to the Thai man and the drug consignment.
Investigations into the possible drug-trafficking activities of the trio are ongoing.
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