BRITAIN'S drugs czar made it clear that he was totally opposed to the legalisation of cannabis at a conference in Aberdeen yesterday, despite evidence from a Dutch police chief that his country's liberal attitude was succeeding.

Rotterdam Police Commissioner Eric Van Der Horst told the International Association of Chiefs of Police that decriminalisation allowed different ways of reaching drug users, and stressed: ''When you look at it as a criminal problem you only have one solution.''

Adding that social atmosphere was more important than political choice, and that an integrated approach was needed, he said: ''Every partner can play his role - the departments of health, justice, the interior and the police authority - to deal with the problem.''

However, Mr Keith Hellawell said he was convinced that in 20 years, cannabis would be recognised as the same health hazard as cigarettes, and stressed the importance of patience for a long campaign against the evil of drugs.

Mr Van Der Horst had said the aim was not to eradicate drug use but to diminish the drug nuisance to a manageable level.

''We will never be able to wipe out society's demand for both legal and illegal intoxicants,'' he claimed.

It was society, he said, which decided what level was manageable or acceptable and it changed. In 1994, in certain parts of Rotterdam, the situation got out of control and a house occupied by drug addicts was set ablaze because the local community did not want drug tourists in their midst.

Subsequently, the authorities tried to help the community to take responsibility for solving its problem and admirable solutions emerged.

Now, all over Rotterdam, there are ''user rooms'' managed by people from each area. He said the problems were not caused by the drug users but by the drug guides paid commission to lead people to the dealers' houses.

He said as a result of the Dutch initiative the number of drug users was declining and the age of drugs users was continuing to rise.

''The average age of heroin and cocaine users is now over 30, and among those under 21 it is diminishing rapidly. They do use cannabis once in a while but, in my view, that is seeking the experience, like the first cigarette or the first beer.''

Mr Van Der Horst added: ''I think our efforts should be directed at drug traffickers rather than users.''

Mr Hellawell also said that the focus should be on reducing the availability of drugs, and said everyone was of a like mind at international conferences, but ''not always did they deliver against fine words''.

''The activities of Governments ought to be on what really is happening in countries that grow and process drugs. What is happening in countries through which the bulk of these drugs come and across whose borders these drugs travel.''

He also said honesty and consistency were necessary in warning youngsters about the dangers of drugs.

''They are getting so many messages on the streets about drugs, so many messages in newspapers, messages from relatives and from friends.

''We need clarity in the messages we give and we have to be careful with messages.''

Mr Hellawell said: ''Young people are not silly and have their own experiences and shared experiences. We have to be honest and do a lot of research in the messages we are giving to understand the effect they have, and we need to be consistent with these messages.''

He stressed that when investing in children we had to be patient.

''Sometimes people who have real problems associated with something such as drugs don't want to be patient.

''My view is that if they are looking for short-term solutions and believe something like my appointment is going to change something as complex as the drug problem, they are wasting our and the community's time.''