Drug pressure groups today welcomed a call to legalise cannabis by former Conservative Party deputy leader Peter Lilley.

Mr Lilley, writing in today's Daily Telegraph, urged Tory leadership contenders to urgently think about liberalising the laws on cannabis.

His comments were welcomed by drugs charity Release, which said a change in cannabis laws was "long overdue."

Mr Lilley argued, in a move likely to shock many Tory traditionalists, that one of the biggest handicaps the Conservatives faced during the General Election was the perception that their policies were negative and punitive.

"On crime and asylum-seekers as well as drugs, Conservatism seemed to be about locking people up," he wrote.

"It ought to be about setting people free.

Nothing could more vividly dramatise reaffirmation of our belief in freedom and personal responsibility than to move clearly in favour of liberalising the law on cannabis."

The Social Market Foundation think-tank was today publishing a pamphlet by Mr Lilley in which he argues that the law on cannabis use is unenforceable and indefensible in a country in which alcohol and nicotine are legal.

He envisages that magistrates could issue licences for outlets selling cannabis to over-18s.

Consumption would not be allowed on the premises or in public places and a limit would be imposed on the amount sold.

The drug would be taxed and carry a health warning. Cultivation for personal use would be permitted.

Mike Goodman, director of the drugs charity Release, welcomed Mr Lilley's comments, saying: "The debate in relation to cannabis has really come on leaps and bounds in the last few months.

"We're now having a much more sophisticated discussion and it's good that it is coming through leading politicians. The law on cannabis is long overdue for reform."

Cannabis should be down-rated from a class B to class C drug, he said, adding that more debate was needed on whether it should be decriminalised or legalised.

"We need to start thinking about how we can change the law. We need to start addressing issues such as quality control, consumer protection and how we can protect children from it," he said.

"If we decide we want to go along that road, I'm sure in a couple of years we will look back and wonder what all the fuss is about."

Last night, on BBC 1's Question Time, shadow chancellor Michael Portillo said the Conservative Party had to be prepared to engage in a debate about calls for the legalisation of cannabis.

Mr Portillo said: "I think the arguments on both sides are quite finely balanced, and I think they are complicated. But a Conservative Party that I led would certainly be happy to address those issues ...

"We should be the party that is open to new thinking ... yes, we would consider this question."

A Home Office spokesman said: "The Government's policy has not changed.

"We have a clear and consistent view. There are no plans to legalise or decriminalise cannabis or any other controlled substances."

Despite his previous position as deputy leader of the Conservative Party, Mr Lilley was just another individual calling for cannabis reform, he added.

But shadow home secretary Ann Widdecombe warned that legalising cannabis would lead drugs barons to push even more hard drugs.

Miss Widdecombe - whose proposals for zero tolerance of cannabis fell flat when a succession of shadow cabinet members admitted to having tried the drug - said: "The current position of the Conservative Party is that we are opposed to legalisation and, indeed, decriminalisation.

"I would myself wonder what we would expect the big drugs barons to do if we legalise cannabis. I think it is very unlikely that they would just go home.

"It would be far more likely that they would put a huge amount of their effort into marketing hard drugs and probably targeting ever younger age groups," she told the BBC Radio 4 Today programme.

But Mr Lilley said the law was "indefensible" and compared it with prohibition in the United States.

"More people actually try cannabis in this country than in states where it is legally available," he told the programme.

"The reason that it is unenforceable is that it is indefensible. The argument that it has serious health risks has been effectively demolished by the Lancet study which concluded that on the medical evidence available moderate indulgence in cannabis has little ill effect in health. Any ban on cannabis should be based on other considerations."

The argument that cannabis was a "gateway" drug which led to harder drug use was the most serious consideration, Mr Lilley said.

"I concluded, as did Lancet, that there is no way that taking cannabis encourages you chemically, or predisposes you to taking hard drugs," he said.

"What we have actually is the perverse situation that by making cannabis illegal it is only available through illegal sources, which are the same channels that handle hard drugs.

"So we are forcing cannabis users into the arms of hard drugs pushers.

"It is that link I wish to break by providing same regulated off-licence outlets for people to get cannabis if they want to have it without being brought into contact with the hard drug pushers."

Miss Widdecombe's argument about drug barons was "slightly strange", Mr Lilley said, adding: "They will become much less big and much less rich if they don't have the rich pickings of cannabis.

"At present because it is illegal they can make big profits out of it. If there were legal channels they would not do so.

"But the idea that we should provide them with a drug to sort of divert their attentions from heroin I find slight strange."

Mr Lilley said his proposals did not amount to a "trade in cannabis" and would involve strict regulation.

He was confident it would come about "in due course".

He said he had never tried the drug, adding: "I have no desire to do so.

"What I do believe in however, is freedom and personal responsibility."

Mr Lilley is backing Michael Portillo in the Tory leadership contest but said he had not discussed his proposals with the shadow chancellor.

"I sent him a copy last night of the pamphlet as I did the other leadership candidates so that they would be able to comment on it if asked," he said.

"I hope they will realise that the Conservative Party has to face up to these difficult issues and to reach out to sections of the population who we did not make contact with at the election.

"The young, the ethnic minorities who come into contact with these laws, who know they are ridiculous, would look at us in a different light if we had the realism to do so."