Trainspotting author Irvine Welsh is reluctant to back growing calls to legalise narcotics because drug dealers' vast profits would go to pharmaceutical giants instead.

Pro-drug campaign groups believe recent moves to decriminalise marijuana in U.S. states including Colorado and Washington, and the Uruguayan government's decision to completely legalise the drug, point to a change in approach towards the issue.

Scottish author Welsh, whose book telling the story of a group of heroin addicts was immortalised in the 1996 movie starring Ewan MCGregor, wants drugs to be made legal but fears it will simply drive the profits away from street dealers who are struggling to survive.

He tells The Independent Magazine, "One of the only reasons I'm reticent about legalising drugs is because there's so little for ordinary people now. If you take the criminal class, the black economy, out of the equation, there's absolutely nothing for ordinary people. The profits go to pharmacies and and multi-national corporations and chemists."