Chris Davies, leader of the Liberal Democrats in the European Parliament, believes the only way to stop the criminal drugs trade is to legalise all forms of drugs and arrange for them to be sold legally.
The MEP said selling drugs under a regulated regime is the only way to beat the traffickers and stop billions of pounds reaching the "pockets of criminals and funding terrorist activities".
His remarks are bound to embarrass the party leadership, which opposes legalising hard drugs but faced awkward questions about its drugs policy during the general election.
The leader of the party's Euro MPs has accused politicians of ignoring the problem of drug abuse and says drastic action must now be taken to prevent the rise in drug addiction, and resulting criminal behaviour.
He said only "a legally regulated market in drugs like cannabis and heroin could reduce crime affecting society".
"The debate now should be about how to destroy the criminal trade by providing the regulated legal sources while discouraging giving the impression that it would create a green light for drugs use," he said.
A recent report by Lord Birt, the Prime Minister's "blue-skies thinker", found there are almost 300,000 drug users who commit crimes to feed their habit in the UK. The cost of that criminality is £16bn a year - or £24bn if the costs to the nation's health and "social functioning harms" are added.
The report estimated three million people in the UK use illegal drugs, and 749 people die annually from heroin and methadone use.
Writing in the Brussels magazine, The Sprout, Mr Davies argues that, by selling drugs off the shelf, you could ensure that pure drugs, rather than contaminated drugs, would reach the market.
He said details have yet to be worked out but that the Dutch model, where cannabis is available for purchase, had not led to an increase in cannabis use.
The party tried to distance itself from the view. "This is certainly not party policy," said a spokesman.