Ms Short said drugs were at the root of crime

She said the present policy was not working and 67% of crime was linked to drugs.

The former international development secretary, who resigned in protest following the war in Iraq, said a rethink was needed.

"I'm not saying that it is a good thing to take hard drugs," she told ITV1's Sunday Supplement.

"But what I am saying is that present policies are not working and the drug problem is growing and is a major part of Britain's crime problem."

"We need to look at the effects and how we are dealing with it."

We should have free clean drugs available on the National Health Service to enable addicts to disconnect from criminality Clare Short

Last year Home Secretary David Blunkett announced cannabis was to be reclassified as a less dangerous drug.

He said it would allow police officers to concentrate on hard drugs such as heroin and cocaine and dealers.

But Ms Short said drugs were still at the root of Britain's crime, and she would put it in the top three subjects in the new Labour manifesto.

She said: "We should have free clean drugs available on the National Health Service to enable addicts to disconnect from criminality and then give them a better chance to change their lives."

Shadow Home Secretary Oliver Letwin agreed hard drugs fuel a lot of the country's crime, but said treatment and rehabilitation was the best solution.

He said: "If it were Clare Short's own children involved, we believe that she would not want them to be given hard drugs on the NHS.

"She would want what all other parents in that position want - namely, serious intensive abstinence-based treatment and rehabilitation for young people on hard drugs."

Green deputy mayor of London Jenny Jones backed Ms Short's comments on Saturday.

She said free heroin on the NHS would break the cycle of drug addiction and the crimes committed to fund it.