Officers burst into an illegal drug lab and arrest suspects before a HazMat team decked out in orange suits moves in to contain the scene.

This may seem like something out of a movie, but it unfolded here on Dec 6 last year, in what is believed to be the first suspected case of drug manufacturing in Singapore in recent years.

The Central Narcotics Bureau (CNB) raid, supported by the Singapore Civil Defence Force and Health Sciences Authority, resulted in the arrest of two men, aged 40 and 45. The authorities also seized 2.6kg of synthetic cannabis and 500g of an "unknown powdery substance".

A CNB spokesman told The Straits Times that there have been no drug manufacturing cases here in "recent years". "Singapore's zero-tolerance stance on drugs and our vigorous enforcement actions served as an effective deterrent in keeping such nefarious activities out of Singapore," he added.

If convicted of unauthorised manufacturing of a Class A controlled drug, the pair arrested in the Dec 6 raid each face at least 10 years' jail and five strokes of the cane.

When ST visited the industrial unit where the drugs were believed to have been made, neighbours said they did not suspect a thing and had hardly interacted with the employees there. A sign on the door indicated that the unit housed a ship supplies company.

The management of the industrial building in Yishun Industrial Street 1 declined to comment, and attempts to contact the unit's owner went unanswered.

Mr Wu Jia Wei, 30, a partner of a cleaning company next to the unit, was shocked to discover what had allegedly been going on just next door: "There was no strange smell, no unusual noises. It was actually very quiet."

Lawyer Amarick Gill, who has been practising law for 20 years, said: "(Drug) cases are usually possession, consumption, trafficking or importation of drugs. I've never come across a case of manufacturing before."

Typically, drugs are made in other countries, and traffickers or abusers are caught when they try to bring them into Singapore, he said.

"The Tuas and Woodlands checkpoints are the usual points where drugs are intercepted before they reach our shores. Traffickers or abusers are also caught during spot checks or when the authorities act on tip-offs," he added.

Synthetic cannabis, also known as synthetic cannabinoids, is classified as a new psychoactive substance (NPS) and is a Class A controlled drug.

It is sometimes referred to as "spice" or "K2" and is usually packaged as dried plant material laced with fragrances and spiked with a synthetic cannabinoid.

While its molecular structure differs from the active molecule in the cannabis plant, synthetic cannabis acts on the same receptors in the brain to create a similar effect, said Dr Too Heng Phon, an associate professor at the National University of Singapore's biochemistry department.

Traffickers manufacture these sorts of drugs in many countries, said sociologist Stella Quah. "It is typically done in improvised hidden labs... as they find it increasingly difficult to avoid police surveillance when they try to bring illicit drugs into the country."

Professor Quah, an adjunct professor at the Duke-NUS Medical School, noted that it has become a trend elsewhere for addicts to try manufacturing illegal drugs, although such activity is difficult to hide in Singapore.

But there is the threat that the manufacture of these new kinds of homemade drugs might spread here because of the availability of information online, she noted.

"Drug users might be deceived into thinking that it is easy to do so.

"The dangers of 'cooking drugs' at home and consuming them range from the serious risks of handling volatile chemicals without protective gear and equipment, to injecting or consuming cheap, non-purified hazardous substances."

Dr Edmund Tian, domain lead of chemistry testing at Temasek Polytechnic's School of Applied Science, noted that the quality of such drugs may not meet pharmaceutical standards and "are often contaminated with synthetic by-products and derivatives originating from inefficient synthetic processes". "These chemicals could be even more toxic to humans."

He added that cardiovascular problems and psychological disorders like panic attacks are among frequently reported symptoms of NPS.

Dr Too warned: "Synthetic cannabis can contain other highly toxic substances with its chemical make-up varying from batch to batch. You never know what's inside."