Nick Clegg’s call for the reform of drug laws appear to have gone up in smoke after David Cameron insisted the current approach was working.
Speaking at a press conference in Brussels on Friday, the prime minister rejected Clegg's suggestion that a Royal Commission be set up to examine whether current drug laws should be relaxed.
The disagreement is the latest public crack in the coalition, following a fundamental disagreement over the Leveson Report and internal wrangling over tax policies announced in the Autumn Statement.
"I don't support decriminalisation of some drugs that are currently illegal," Cameron said.
"The deputy prime minister is entirely entitled to take a view for the next election and beyond".
On Friday the deputy prime minister said Britain's drug policies are failing, in direct opposition to Cameron who ruled out a review into the government's approach earlier this week.
The leader of the Liberal Democrats called on the prime minister to show courage in waging a war against drugs, calling for a reform of drugs laws.
In an interview with the the Sun, Clegg said: "If you were waging any other war where you have 2,000 fatalities a year, your enemies are making billions in profit, constantly throwing new weapons at you and targeting more young people, you'd have to say you are losing and it's time to do something different.
"I'm anti-drugs - it's for that reason I'm pro-reform."
He insisted he is not in favour of full legalisation of drugs but thinks targeting dealers and traffickers, while decriminalising possession, might be a solution.
The Commons home affairs committee found the government's drugs policies to be failing in a report published on Monday, and recommended a royal commission to look at alternatives.
He told the Sun he will include a "clear commitment" to a royal commission on drugs in his party's 2015 manifesto.
He added: "I told the Prime minister that this was a missed opportunity. He knows my views on this. He and I don't agree on this."
Clegg told the BBC there was a "conspiracy of silence" over the failing drugs laws because policies to tackle the problem, such as decriminalisation, are seen as "too controversial."
However despite his disagreement with Cameron, he told the BBC: "I don't see this as a thing between myself and the prime minister. It's what do we as a country believe is the right thing to do."
The Lib Dem leader said he has ordered Home Office minister Jeremy Browne to compile a report on liberal approaches to drugs across the world which have worked, including in Portugal, Amsterdam, Latin America and several US states.
The home affair’s committee’s recommendations are similar to those made by its last in-depth study into drug laws in 2002 which suggested the relaxation of drug laws when Cameron was a member.
Cameron poked fun at his changed position on the issue on Friday, telling reporters: "I have said all sorts of things about drugs policy over the years."