Deputy PM angry at Tory refusal to debate alternatives and says: 'If you are anti-drugs, you should be pro-reform'

Nick Clegg has dragged the case for reforming the drugs laws to the centre ground of British politics, saying that blanket prohibition has seen cocaine use triple in less than 20 years, a trend that has helped perpetuate conflict and violence in South America.

Writing in today's Observer, after a week in which he visited Colombia to learn first-hand the devastating effects that Europe's enthusiasm for cocaine has had on the country, Clegg said the UK needed to be at the heart of the debate about potential alternatives to blanket prohibition and that he wanted to see an end to "the tradition where politicians only talk about drugs reform when they have left office because they fear the political consequences".

The deputy prime minister said such an approach "has stifled debate and inhibited a proper examination of our approach. Put simply, if you are anti-drugs, you should be pro-reform".

His comments will be seen by some observers as politically expedient, designed to distance the Lib Dems from the Tories in the runup to the next election. In his article, Clegg expresses his frustration "at my coalition partner's refusal to engage in a proper discussion about the drugs problem".

In some of the most outspoken comments on the issue by a serving British politician, Clegg laments the current situation in which "one in five young people have admitted taking drugs in the last year", and "cocaine use has more than trebled since 1996" and claims that "every time someone dies of an overdose it should shame our political class".

Looking to 2016, when the UN is due to hold a meeting to discuss potential reform of its prohibitionist drug conventions, Clegg states: "The UN drug conventions badly need revising. I want European countries to work together to agree a common position in favour of reform to take to that discussion in 2016. The UK can lead the debate in Europe and Europe can lead the debate in the world. But we must be prepared to start afresh with a new mindset and be prepared to do things differently."

His intervention comes as a growing number of US states move towards a regulated trade in marijuana, and at a time when increasing numbers of Latin American countries have stated that the war on drugs doesn't work and are demanding that the world consider alternative approaches.

During his visit, Clegg met the country's president, Juan Manuel Santos, as well as former paramilitaries, guerrillas and human rights representatives. "All were clear about the central role of the drugs trade in perpetuating conflict and violence and the need to build a better future," Clegg says. "Many people in Britain and the rest of Europe will be unaware of the impact drug use in western nations has on countries on the frontline of the drugs trade."

Reiterating his call for a royal commission on Britain's drugs laws, Clegg says future legislation should be based on "what works, not guesswork". The Lib Dems are conducting a review of international alternatives which will produce what Clegg claims is "the first proper UK government report examining different approaches in other countries".

It is clear the deputy prime minister believes there is a need for politicians of all parties to confront an issue in a non-partisan way if the harm caused by drugs is ever to be tackled successfully.

"If Britain were fighting a war where 2,000 people died every year, where increasing numbers of our young people were recruited by the enemy and our opponents were always a step ahead, there would be outcry and loud calls for change," Clegg says. "Yet this is exactly the situation with the so-called "war on drugs" and for far too long we have resisted a proper debate about the need for a different strategy."

His comments, which will dismay those who believe change will encourage drug taking, were warmly received by pro-reform campaigners.

"Bad drug policies have an international impact, whether it's black market related violence or borderless health crises," said Kasia Malinowska-Sempruch, director of the Open Society Global Drug Policy Foundation. "So charting a new course is the job of every country. A number of European countries developed great health services for people who use drugs but far less attention has been paid to the issues faced by producer and transit countries."