Michael Howard has pledged to reverse the government's decision to reclassify cannabis.

In an interview with Thursday's Independent, the Tory leader says ministers are sending out a confused message about recreational use of the drug.

But home secretary David Blunkett claimed the government was not going soft on the issue of drug use.

The change in the law comes into force in a week's time but the move has been challenged by doctors who link the drug's use to psychiatric problems.

He said the decision to change the law on the drug will create a "massive muddle in the middle".

"This is not a simple argument about being hard on drugs or soft on drugs. There are two perfectly arguable positions you can hold on the question of cannabis," he said.

"One is to say that it should be legalised. There are arguments which I understand for that - about personal liberty and that it would cut links with dealers.

"There are arguments for keeping it as it is now - everyone knows where they stand; it is a Class B drug; all the consequences of the criminal law are available and it sends a message that it is an activity which is against the law.

"It seems to me that there is absolutely no case for what is a massive muddle in the middle."

The move comes as the government launches a £1 million PR campaign to send out the message that dope will remain an illegal substance despite next week's reclassification.

In an interview with Thursday's Times, David Blunkett, reveals that he expects to "take a lot of stick" over his decision to reclassify the drug.

"I would be lying if I did not say we agonised over this all the way along," he told the paper.

"I have not started to agonise. I did when we started to address what we were going to do because there are major contradictions."

Blunkett defended the government's position, arguing the message was not that using cannabis was acceptable.

"What we are saying is that cannabis is illegal. For some people it is dangerous," he said.

"For others it is destructive, so don't do it. You don't need drugs to get through life. But for young people, let us be clear that crack will drive you bonkers and heroin will destroy your life. Both are potential killers. That is a simple and powerful message."

Blunkett believed alternative policy ideas were unlikely to succeed.

"If there is a politician who believes they have the definitive answer on drugs, I would like to know who they are," he said.

"It is the challenge of the next two decades. Its destructive power in terms of criminality, fracturing of families and communities is devastating."

He was backed by Mark Oaten, the Liberal Democrat home affairs spokesman, who said the Conservatives should "get real" on the issue.

"The Conservatives are just burying their heads in the sand," he said.

"Whilst cannabis, like any drug, is harmful, reclassification does make sense. But only if it is matched by the police retargeting resources on the hard and more dangerous drugs, and dealers who cause so much crime in our country."