Drugs such as LSD and MDMA should be decriminalised and sold in pharmacies, the government's former chief drug advisor has said.

Professor David Nutt said that many substances currently banned are no more toxic than alcohol and that the potential penalty and criminal record which go with them amount to more harm than the drugs themselves.

"They should be decriminalised, there is no doubt about that. It is clear, if you are using a drug less dangerous than alcohol, that is a rational choice. If, like crack cocaine, it is more harmful of course, that is different. Addiction is also another matter but it requires treatment," he told reporters yesterday.

He added that he was not in favour of full legalisation and "selling heroin in supermarkets" but said a system whereby drugs - including Class A substances - were sold in pharmacies could work.

Professor Nutt said: "It is clear that the best way of preventing people from coming to harm is education. People need to know what they are doing. I do not see any reason why people should not access drugs like cannabis or MDMA through a pharmacy.

"At least then, you would know what you are getting. You could then deal with the issues under things like trade laws; that would give people a great deal of safety. When BZP was being made available in New Zealand, under this system, it was made by companies to a very high quality."

But he added that he would not advocate people being allowed to simply buy up stocks of the most harmful drugs, like heroin.

Professor Nutt was sacked by the government nearly three years ago after a turbulent relationship with two Home Secretaries: Jacqui Smith and Alan Johnson, who sacked him after comparing the dangers of drug use with the dangers of horse riding.

He argued he was simply trying to provide perspective on the perils and, as he left the unpaid post, accused ministers of undermining scientists.

Launching his book "Drugs - without the hot air" yesterday, he also claimed that the criminalisation of many drugs which may have medicinal benefits has dealt a greater blow to science than the opposition to stem cell research.

He claimed that difficulties with obtaining licenses and reliable samples of the most tightly controlled substances meant that potentially helpful drugs were not being researched.

"Before LSD was banned in 1965, there were lots of studies done, since then, there has been one," he said.