Home Secretary Alan Johnson has told MPs that he "lost confidence" in Professor David Nutt's ability to be his principal adviser on drugs policy after he had "acted in a way that undermined the government".
Mr Johnson argued that some of Prof Nutt's recent comments on drugs policy, including the claim that former Home Secretary Jacqui Smith was guilty of "distorting and devaluing" scientific research, were made without prior notice to the Home Office and in breach of guidelines.
in the Commons on 2 November, Mr Johnson said he asked Prof Nutt to resign because his role was "to advise rather than criticise government policy".
But he insisted his dismissal was "not a reflection" on the work of the Advisory Council on the Misuse of Drugs (ACMD) and he would be meeting other members "shortly".
Two members of the ACMD have already quit after the sacking of Prof Nutt and others are threatening to follow.
To cheers from the Conservative benches, shadow home secretary Chris Grayling said Mr Johnson's decision was "the right one".