While social workers agreed that fewer young people were taking drugs, they said the figures might not be a true reflection of the picture as many were going to the mainland for cheaper drugs.

'The drop is partly caused by the redistribution of youth drug addicts. More young people are going back to the mainland for drugs as there has been less large-scale combatting of the problem on the mainland recently,' said Luk Kwai-kwok, an outreach social worker from the Federation of Youth Groups.

'Fridays, weekends and school holidays are when students will make those overnight trips.'

Mr Luk agreed that while recent anti-drug police operations in Hong Kong had been successful in deterring young people from using drugs, similar actions were needed across the border, especially on school holidays.

The overall number of newly reported abusers also decreased by 22.4 per cent from 4,036 to 3,132. There were 1,152 new drug abusers aged under 21, 32 per cent down from 1,695 last year.

Hong Kong Playground Association outreach social worker Wang Yiu said young people were more vulnerable to drugs during the festive season.

But he believed shifts in youth culture and the poor economy meant fewer young people were interested in spending their money on drugs.

According to government figures, the most commonly abused drug in all age groups was heroin, at 77.1 per cent, and for people under 21 ketamine, at 59.7 per cent.

But skewing the figures is that only users who have registered for treatment or been referred for help by social workers are included in the numbers.

'Young people are getting less pocket money now as family income drops, especially after Sars,' Mr Wang said.

'Drugs, compared to sports or internet games, are too expensive to them.

'And drugs are no longer chic to them as they realise the adverse effects of drugs, either through public education or seeing the sufferings of their buddies.'