Nearly 2,000 litres of illegal cough syrup worth an estimated $1,25 million were seized in a three-month operation by the authorities.

From April to July, the Health Sciences Authority and the Central Narcotics Bureau uncovered the codeine-containing syrup from an illegal supply chain. Four Singaporean men have been arrested for the offences.

Investigators found that the 3.8 litre canisters of cough syrup were brought into Singapore by passing them off as tyre shine, porcelain cleaners and degreasers.

While codeine cough syrups are used to treat coughs, they can cause addiction if used without proper medical supervision. When taken in large amounts, it can cause hallucinations and even death.