The Government's chief drugs adviser was forced to resign in the wake of the row over the dangers of class A drugs.
Home Secretary Alan Johnson asked Professor David Nutt to resign as chairman of the Advisory Council on the Misuse of Drugs (ACMD), saying he had “lost confidence” in his ability to give impartial advice.
He accused Prof Nutt of going beyond his remit as an evidence-based scientist and accused him of “lobbying for a change in Government policy”.
But Prof Nutt hit back, accusing the Government of “misleading” the public in its messages about drugs and of “Luddite” tendencies.
He linked his sacking to “political” considerations, citing the forthcoming election.
Professor Nutt sparked controversy this week when he said ecstasy and LSD were less harmful than alcohol and cigarettes, and criticised the decision to upgrade cannabis to class B.
Speaking after he agreed to step down Prof Nutt said: “It's unusual political times, I suppose, elections and all that. It's disappointing.
“But politics is politics and science is science and there's a bit of a tension between them sometimes.”
He attacked Prime Minister Gordon Brown for making what he said were “completely irrational” statements about cannabis.
Confessing himself “extremely surprised” by the decision, he said: “The danger is they (politicians) are misleading us. The scientific evidence is there, it's in all the reports we published.”
The row erupted earlier this week when, in a paper for the Centre for Crime and Justice Studies at King's College, London, Prof Nutt attacked what he called the “artificial” separation of alcohol and tobacco from other, illegal, drugs. All drugs, including alcohol and tobacco, should be ranked by a “harm” index, he said, with alcohol coming fifth behind cocaine, heroin, barbiturates and methadone. Tobacco should rank ninth ahead of cannabis, LSD and ecstasy, he said.