David Macauley also said the failure to prosecute the son of Jack Straw, the Home Secretary, for selling cannabis gave young people a "confused message".
Mr Macauley stood down in protest from his pounds 40,000-a-year post as the director of Scotland Against Drugs, which receives a pounds 500,000 grant from the Scottish Office to develop community programmes.
He said he is strongly in favour of the "just say no" approach to drugs and believes the decision to entertain Noel Gallagher - who argued that the taking of drugs was as normal as drinking a cup of tea - at No 10 was a mistake.
"It's not just me criticising Tony Blair; the young people I talk to say they felt he was supporting drug taking. The Gallaghers are in their magazines and on the television and that message is getting across,'' he said.
He added: "Noel Gallagher's PR people would never let him go on television and say things that were racist. We need to apply the same rules to drug abuse."
Mr Macauley also feels the treatment of William Straw, 17, who received a caution, was a symptom of government-led confusion. "If you are caught drunk-driving in Ayr or Sauchie you know it's unacceptable and you'll get banned. If you're caught with a couple of joints, prosecution depends on where you are. It confuses the police and the public."
He added that he was angry at his organisation's budget being cut from pounds 2m to pounds 500,000 and having to deal with the Government's "confused message, if there is one at all" on the drug problem.
Critics of Mr Macauley's approach to drug prevention have argued that he has stuck with the single message of "saying no", which they believe is only effective for a few people.
A Scottish Office spokesman said: "We always favour a broad approach when dealing with drug abuse."
t Women, teenagers and ethnic minorities who are drug abusers are to be targeted in a multimillion-pound prevention strategy announced yesterday. The government initiative follows evidence that there are only enough treatment places to help one in every five problem drug takers. Current treatment services tend to concentrate more on white men aged from 20 to 35.