Two men were arrested on suspicion of manufacturing controlled drugs on Wednesday.
The operation, led by the Central Narcotics Bureau (CNB) and supported by the Singapore Civil Defence Force (SCDF) and the Health Sciences Authority (HSA), saw the seizure of about 2.6kg of synthetic cannabis, the three agencies said in a joint statement yesterday.
CNB officers were at Yishun Industrial Street 1 on Wednesday morning to observe two suspected drug offenders.
The suspects - both Singaporean men aged 40 and 45 - were spotted separately entering a unit in the industrial building. CNB officers then raided the unit and arrested them.
While inside, they detected a pungent smell and quickly fled the unit with the two men.
A team of SCDF's HazMat (Hazardous Materials) specialists entered the unit to investigate the smell.
They determined that the air within the room was hazardous and proceeded to carry out controlled ventilation of the room.
Once the unit was declared safe to enter, CNB and HSA officers conducted a thorough search of the unit.
The search uncovered a total of about 2.6kg of synthetic cannabis and 500g of an "unknown powdery substance".
The two men are being investigated for unauthorised manufacturing of controlled drugs.
If found guilty of unauthorised manufacturing of a Class A controlled drug, the pair face at least 10 years' jail and five strokes of the cane.