Ministers are ploughing on with plans to ban dance drug mephedrone despite the resignation of another government drugs adviser over the issue.
Eric Carlin quit the Advisory Council on the Misuse of Drugs (ACMD) yesterday, saying his decision to stand down was a protest at the way the drug had been criminalised.
A Home Office spokesman said Mr Carlin's resignation was "regrettable" but added: "It does not impact on our plans to ban mephedrone and the other substances as soon as parliamentary times allows."
Mr Carlin has become the second member of the panel to quit over plans to ban mephedrone, also known as miaow miaow, and the seventh to step down after rows over government drugs policy.
Home Secretary Alan Johnson announced the drug would be banned within weeks. The legal high, which has been linked to up to 25 deaths in England and Scotland, will also be made a Class B drug.
In his letter of resignation to Mr Johnson, Mr Carlin said: "We had little or no discussion about how our recommendation to classify this drug would be likely to impact on young people's behaviour. Our decision was unduly based on media and political pressure."
Dr Polly Taylor, a long-standing member of the ACMD, quit hours before Mr Johnson announced plans to ban mephedrone.
Last October, the ACMD was thrown into turmoil after five advisers resigned in protest when chairman Professor David Nutt was effectively sacked by Mr Johnson. The scientist had claimed publicly that ecstasy and LSD were less dangerous that alcohol, leading Mr Johnson to ask him to resign.
Prof Nutt said the council had been placed under "inappropriate pressure" to draw up advice on mephedrone and said: "There's been a terrible pressure to come to a resolution about mephedrone - inappropriate pressure."
Shadow home secretary Chris Grayling said: "After all the chaos of the last few months, it finally looked as if Alan Johnson might be getting things back into shape again. The decision on mephedrone was the right one, but this latest resignation suggests pretty clearly that the Home Secretary has been completely unable to restore his relationship with the experts who advise him."