The former cabinet minister Mo Mowlam has re-ignited the drugs debate with a radical call for the decriminalisation of all drugs - including heroin and cocaine.

The outspoken former minister said legalising, and taxing, all drugs was the only way forward given the prevalence of drug use.

"I am almost at the point - not quite but I'm thinking quite hard about it - of wanting to see all drugs legalised," she said.

Mowlam, who in government was responsible for the government's anti-drugs strategy, said that the government should tax drugs and use the money generated to fund projects to beat addiction.

She dismissed claims that legalising hard drugs would increase the number of users. "This is not me gone completely mad. A lot of social workers agree with me, as do a lot of police," she said.

Her call was dismissed by Tory frontbencher, Theresa May, who warned it would be a step too far.

"If you legalise them all then you potentially increase dependency: because people think it is OK and more people will try it - some of those who at the moment don't and don't move onto hard drugs because of the legal situation,'' she told GMTV's Sunday programme.

Lib Dem home affairs spokesman said that a case could be made for legalisation but warned that it would set Britain at odds with its international counterparts.

"What we have got to do is break the link between the criminal suppliers and people who use drugs whether it is recreational drugs like cannabis or hard drugs like heroin," he said.