The Central Narcotics Bureau (CNB) has raised concern over cannabis abusers as the number of people arrested for using the substance rose 29 per cent from 142 in 2012 to 183 last year amid the broader trend of an increase in the number of drug abusers and drugs seized in 2013.

In its annual drug report released on Friday, CNB's director Ng Ser Song said: "Globally, some jurisdictions have relaxed their stance on the abuse of cannabis, with many seeing it as something relatively harmless. They cannot be more wrong."

Last year, CNB conducted 46 major operations, including 19 island-wide operations, crippling 20 drug syndicates. The island-wide operations targeted middle-level traffickers, street-level pushers and drug abusers, and were strongly supported by the Singapore Police Force, said the agency.

The step-up enforcement saw an increase in the number of drug abusers arrested from 3,507 in 2012 to 3,574 last year. Repeat abusers constituted 69 per cent of all abusers arrested last year.

About half of new abusers arrested are aged between 20 and 29 years old. On the bright side, CNB's statistics showed a drop in the number of new youth abusers below the age of 20, from 162 arrested in 2012 to 152 last year.

Last year, CNB seized a record $20.5 million worth of drugs which was 12 per cent higher from the $18.3 million worth of drugs seized in 2012. The quantity of "Ice" seized in 2013 remained high, at 43.99kg. About 80 per cent of "Ice" seized were not intended for the local market, said CNB.