The Central Narcotics Bureau (CNB) has seized more than 7.5kg heroin estimated to be worth more than $520,000 in two separate operations over the past week.
CNB said this is its largest heroin seizure this year.
On July 27, CNB officers observed a 50-year-old man meeting a suspected drug client in the vicinity of Tampines Street 21, according to a statement.
Officers subsequently arrested the 60-year-old client and recovered about 1.4kg of heroin from him. They raided the man's unit and arrested a 48-year-old suspected drug abuser. Officers also recovered 0.65kg of heroin and a small amount of ice.
The 50-year-old trafficker was later arrested after meeting a 52-year-old man in Chai Chee.
About 0.47kg of heroin wrapped in instant noodle packaging was recovered from the latter.
Cash amounting to $6,200 was also found on the 50-year-old man. A search of his hideout at a building in Woodlands Link uncovered two Erimin-5 tablets and a small amount of Ice and heroin. Similar instant noodle packaging material was also found.
In the second operation on July 29, CNB officers observed a 56-year-old drug trafficking suspect meeting with a 36-year-old Malaysian man around the vicinity of Circuit Road at about 8.20pm.
The younger man, along with his suspected accomplice - a 28-year-old female Malaysian, and the 56-year-old man were arrested shortly after.
At the hideout of the older man, officers seized about 4kg of heroin, some of which were concealed in heat-sealed food packaging.
The drugs seized were worth about $280,000. Over $72,000 in cash and some foreign currency were also recovered.
Investigations into the drug activities of all the suspects are ongoing.
Drug offenders found guilty of trafficking diamorphine (or pure heroin) exceeding 15g face the death penalty.