The head of Britain’s leading medical research organisation rounded on the government yesterday for sacking its principal drugs adviser.

Sir Leszek Borysiewicz, chief executive of the Medical Research Council, said scientists must be allowed to give “unfettered advice without the fear of reprisal”.

His criticism followed the abrupt dismissal of David Nutt on Friday. This weekend Nutt said many of his colleagues on the advisory council on the misuse of drugs, which he chaired, could resign in protest. “I wouldn’t be surprised if some of them stepped down,” he said. “Maybe all of them will.”

Nutt suspects he is the victim of a Downing Street plot to oust him and said Gordon Brown was “politically terrified” of his committee’s advice to downgrade classification of the drug ecstasy. He claimed No 10 had repeatedly briefed against his proposals to bring in lesser penalties for the possession of cannabis.

Nutt said he had been sacked for telling the public the truth about drugs. “I’m extremely disappointed that the government isn’t prepared to have a mature and robust discussion about the drugs issue,” he said.

Nutt was sacked as head of the council after claiming in an academic article that alcohol and tobacco were more harmful than some illegal drugs. He has also criticised Brown’s decision to upgrade cannabis to a class B drug, imposing a penalty of five years in prison for users.

Alan Johnson, the home secretary, wrote to Nutt on Friday, saying his views were creating public confusion and relieved him of his post. He said he had lost confidence in Nutt’s ability to give impartial advice.

Nutt, however, said: “It seemed an unnecessarily heavy-handed response. Scientists should be challenging. But obviously he didn’t feel like being challenged.”

The affair has provoked outrage among scientists. Borysiewicz said: “We wholeheartedly defend academic freedom and the need for scientists to present findings based on sound research.

“It is crucial that UK policy is based on evidence and that scientists are able to offer unfettered advice without fear of reprisal. This principle should be the backbone of scientific engagement with government.”

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