The annual British Crime Survey, due out this month, is expected to show that while the price of the drug is falling, its purity "on the streets" is rising.

Steve Taylor, of the Standing Conference on Drug Abuse, said trends meant the drug was finding a new market of recreational users.

Tom Parker-Bowles is alleged to have used cocaine and cannabis

"We are hearing from various sources, including our members, that there are an increasing number of users, particularly young people," he said.

Earlier this year Camilla Parker Bowles' son Tom was reported to be "high on coke" while at the Cannes Film Festival.

Pat Littlewood of the Standing Conference on Drug Abuse: Cocaine sold as 'hip'

And Former England captain Lawrence Dallaglio will face charges of bringing the game of rugby into disrepute and taking recreational drugs on the British Lions tour of South Africa in 1997 at a disciplinary hearing starting on 25 August.

Mr Taylor added: "We have seen a pattern of increasing recreational use in a number of drugs, including cocaine.

"The drug has hit the club scene and as young people have got more into ecstasy and amphetamines, they have increasingly turned to cocaine as well.

"The price has come down and more and more people are prepared to experiment with it."

Exhilaration and depression

Cocaine is a stimulant that causes a feeling of exhilaration and decreases appetite.

When it is snorted its effects wear off within 15 minutes to half an hour, so it has to be taken every 20 minutes to maintain its effect.

Common side-effects after coming down from the drug include depression and tiredness.