Researchers surveyed drug prices in 15 towns and cities - ketamine, which is commonly used by vets, cost an average of �31 a gram.

But the survey revealed it is on sale for �15 in some areas of Nottingham. Only London has similar prices.

It is currently legal to possess but is set to soon become a class C drug.

The charity DrugScope said the survey revealed a rise in the use of ketamine by clubbers.

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Researchers found it on sale in eight of the towns and cities, while it did not feature at all in the same survey last year.

Ketamine is a general anaesthetic which has been used in hospitals and in veterinary medicine since the 1970s.

But among recreational users it is often used in powder, tablet or liquid form.

Users report euphoria, hallucinations and "dissociative" feelings in which mind and body seem to separate.

But it can be dangerous when taken in conjunction with alcohol or other depressants.

Lowest prices

The survey also revealed Nottingham was the second most-expensive city to buy cocaine, jointly with Ipswich.

DrugScope said the surveys indicated ketamine had established a place alongside the usual dance scene drugs like ecstasy.

It added the low price for the drug in Nottingham could be because there was an abundance of the drug available in the city.

A spokeswoman said: "Prices are lowest where there's the greatest amount, and it's linked to demand as well.

"It can happen when you have got different drug dealers competing with each other, which can drive the prices down.

"You would maybe expect more industrial cities like Birmingham or Manchester to have the lowest prices, but Nottingham does have its own drug problems."