A pilot scheme for voluntary drug tests in schools is expected next year, and the government has pledged to consult the public this year about empowering police officers to conduct mandatory tests on suspects.

Frontline social worker Ken Tsang Kin-chiu, from Young Civics, said the plan amounted to discrimination against young people.

'By imposing the tests on students, the government is putting the blame for drug abuse on them,' he said. 'Drug abuse is a complicated problem, behind which lie a lot of intertwining reasons such as family and economic background.'

Chin Wai-lok, convenor for the Concern Group on Schools' Hegemony, said the plan would alienate students and increase truancy.

'Voluntary testing is a pipe dream,' he said, adding that it infringed students' free will. 'Allowing tests to be carried out at schools is tantamount to devolving law enforcement to schools. Only law enforcement agencies such as customs can conduct hair or urine tests.'

Lawyer Alan Wong Hok-ming, from the Civic Party, said the plan contravened the Basic Law and human rights. 'It's just for the convenience of prosecutors,' he said. 'Introducing drug tests before adequate resources are set aside for drug prevention and counselling work for young drug abusers is like putting the cart before the horse.'

Hong Kong Human Rights Monitor chairman Chong Yiu-kwong agreed. 'Any drug test should be carried out only with the consent of the subject and must be done only after reasonable suspicion is established.'

Unionist lawmaker Lee Cheuk-yan voiced severe doubts about the feasibility of voluntary testing. 'There's no such thing as voluntary in this world,' he said. 'Just as workers are forced to accept pay cuts and unpaid leave now, if parents have signed the consent form, will students dare to object?'

David Wong Fuk-loi, principal assistant secretary for security, said drug tests could ferret out young drug abusers hidden in communities.

'It will be too late if we only take action after kids are hurt,' he said.

'Whether it is voluntary or compulsory, the drug test is a means to the end of protecting young people from the harm of drugs. We are considering whether to bring in compulsory drug testing through legislation. We completely understand the big controversy over privacy and human rights. However, human rights issues might not be the top priority in the face of big social problems. Can we prevent abuse of power [by drug test enforcers] and ensure protection of human rights through legislation?'