Cabinet Office Minister Mo Mowlam - head of the government's anti-drugs campaign - has admitted she smoked cannabis as a student.

Ms Mowlam said she had tried the drug at university and had not enjoyed the experience.

The former Northern Ireland Secretary, speaking to Sky News, explained in a reference to Bill Clinton that unlike the American President she had "inhaled" marijuana.

Her admission came as drugs czar Keith Hellawell used a television appearance to call for an end to witch hunts of politicians accused of experimenting with drugs before they entered public life.

He said honesty about drug taking was essential for the debate on drug use to take place on a higher level.

Ms Mowlam, 50, was pressed about a Sunday Telegraph story saying Tory MPs were calling on her to clarify her past involvement with drugs.

She said: "I haven't made any secret of being a child of the 60s, never have. I wasn't part of the drugs culture, but I have said in previous interviews this isn't a new news story.

"I said I tried marijuana, didn't like it particularly and unlike President Clinton I did inhale. But it wasn't part of my life then and that's what happened."

Ms Mowlam, a Durham University student in the 1960s and a postgraduate politics student at Iowa State University in America in the 1970s, said her experimentation had taken place in America.

She said she was determined to carry on leading the government's anti-drugs campaign.

"I will continue to say to young people, as I have done for the last two months in the job, that taking drugs is not within the law and is not a credible thing to do in your life," she added.

'Ridiculous' to resign

Drugs campaigner Janet Betts, whose teenage daughter Leah died after taking an Ecstasy tablet, said it would be "ridiculous" for Dr Mowlam to be forced to step down.

"All this shows is that Mo Mowlam was a student and, like thousands of others in the 60s and 70s, she experimented with cannabis and in her case did not enjoy it," she said.

"It is ridiculous to say that she should be sacked. Indeed, some would say that it is a good thing she has first-hand experience of drugs if she is heading the Government's drugs campaign."

Shadow Cabinet Office minister Andrew Lansley said: "I appreciate that it is important for Mo Mowlam to answer questions about her past.

"But it remains true that the important thing is not her past experience but that she now continues - with us - to stress to young people in particular the dangers of experimentation with and use of drugs."

Witch hunts

Mr Hellawell said he would be "very surprised" if a proportion of the 659 MPs had not tried drugs.

But he said there needed to be an atmosphere where people in public life could be honest about drugs.

"If there continues to be a denial, or if there continues to be a label on people - you know, `you are a bad person if you ever took drugs' - then we'll never move forward and there needs to be more of the openness," he told GMTV's The Sunday Programme.

"I think we've got to stop this idea of witch-hunts and pointing the finger. The debate needs to be at a much higher level than that," he added.

Mr Hellawell's anti-drugs unit is part of the Cabinet Office presided over by Ms Mowlam.