Specialists also disclosed that the potentially lethal practice known as " speedballing", in which users inject themselves with a mixture of heroin and cocaine, is reaching epidemic levels.

The low prices of many drugs suggests that they are readily available throughout the country and that police and customs are losing the war on drugs.

A new survey of 20 cities and towns in the UK provides an insight into emerging trends, offering a level of local detail rarely seen before. The report by the charity DrugScope found that dealers have been increasingly offering cut-price drugs, with heroin costing £5 a bag in Middlesbrough, and ecstasy as little as 75p a tablet in Cardiff.

Towns such as Gloucester and Penzance - where the price of heroin has dropped from £60 to £40 a gram during the past year - are being targeted with "special offers" to attract new users.

The survey also found that abuse of muscle-enhancing anabolic steroids is becoming a mainstream problem.

Overall drug prices in the UK continued to remain static - suggesting that police and customs action has had little effect on availability. When drugs supply is restricted, prices rise.

A separate report by the United Nations Office on Drugs and Crime has also claimed that Britain has the highest rate of "problem" drug abuse in Europe. It found that nearly one in every 100 of the working-age population was an addict.

The DrugScope report discovered huge regional variation in the cost and availability of drugs.

The purity of drugs also fluctuates throughout the country. In Liverpool a seemingly cheap 0.3g £15 bag of "heroin" is on average only 25 per cent pure.

The cheapest cocaine, £35 a gram, is available in Birmingham and Liverpool - both cities where drugs are generally cheaper than the rest of the country. Cardiff has the cheapest ecstasy pills at £1 each.

Researchers also found that clubbers were using a wide range of drugs, including CK1, GHB, Viagra and a vast array of obscure designer drugs.

But the most alarming development highlighted by the study for the drug charity's Druglink magazine was the rise in "speedballing" or " snowballing" which specialists fear will result in more overdoses, infections, and crime.

The survey of 80 frontline drug agencies and police forces discovered that injecting the heroin and cocaine cocktail, also called "curry and rice" , had risen sharply during the past year in Newcastle, Sheffield, Manchester, London, Bristol, Nottingham, Ipswich and York.

A second study of 100 drug addicts revealed that speedballing was the main method of drug-taking for 80 per cent of those interviewed, compared with 25 per cent a decade ago.

The research by Dr Russell Newcombe at the Manchester drugs charity Lifeline found that speedballers had three times as many convictions as those only using heroin. It said speedballers spent £500 a week on the drugs - £26,000 a year - compared with £110 for heroin-only addicts.

Speedballers say the combined stimulant-sedative effects in one shot complement each other. "You get the euphoric rush of the crack and then the heroin takes the jagged edge off it," said one user.

In a separate study of injecting drug-users, more than half of 1,000 needle exchange clients questioned in Wigan, Reading, Middlesbrough, Manchester, Bristol and Devon had injected a speedball.

Drug agencies are concerned about speedballing because it increases the risk of overdose. People who speedball also inject up to five times more often than heroin-only injectors, which means they are more likely to inject directly into an artery, block veins and get deep vein thrombosis and abscesses.

High-profile deaths attributed to speedballing include the American actors John Belushi, 33, who died in 1982 at a hotel in Los Angeles, and River Phoenix, 23, who died in 1993 outside a nightclub in Hollywood.

A speedball is usually made by crumbling a crack rock into a preheated spoon of heroin and a form of citric acid in water - which makes a soluble cocktail. It is then drawn into a syringe and injected. The average speedball costs £20, £10 each of crack and heroin.

More dealers are selling heroin in £10 bags rather than by the gram, and some parts of the country continue to report dealers offering "discount offers" on combined bags of heroin and crack cocaine, fuelling the speedballing craze. In Liverpool, dealers are offering a free rock of crack for every two £10 bags of heroin bought, while in Ipswich buying a bag of "brown" and "white" together yields a £10 discount on a £30 purchase. In Gloucester, the price of the two drugs has halved since last year and in Penzance an influx of dealers from Liverpool has led to price cuts.

Harry Shapiro, the editor of Druglink, said: "Although speedballing isn't a new phenomenon, it is clearly on the increase and, if this trend continues, it will be bad news for attempts to reduce the spread of injecting-related diseases and the number of drug overdoses."

The survey also found that the popularity of anabolic steroids had rocketed, with significant use in Blackpool, London, Birmingham, Middlesbrough, Nottingham, Torquay, Cardiff, Manchester, Portsmouth, Luton and Newcastle. Traditionally used by bodybuilders, the drugs are now being taken by other young people simply to improve their physique. They risk side-effects including reduced sperm count, kidney and liver problems, high blood pressure and increased aggression.

Drug nation

BELFAST

Morphine sulphate tablets, stolen from NHS, popular. Most expensive heroin (£100 a gram) and crack (£25 a rock) in UK

GLASGOW

Crystal meth, form of powdered ecstasy, replacing tablets; skunk popular; 111 drug-related deaths last year

NEWCASTLE

Cheapest cannabis resin (£30 an ounce) and second cheapest amphetamine (£8 a gram) although this has risen from £2 the previous year

MIDDLESBROUGH

Cheapest heroin in UK: one fifth of a gram just £5. Low price attributed to town's role as major drugs transit hub for the North-east

YORK

UK's cheapest ketamine, an animal anaesthetic (£10 per gram). Heroin £50 a gram, more expensive than average

BLACKPOOL

Ecstasy pills as cheap as 75p each when bought in bulk. Ketamine £20 a gram. Viagra and GHB popular among clubbers

MANCHESTER

Below-average price for cocaine (£40 a gram) and crack (£10 a rock). Substantial rise in use of steroids among young men

LIVERPOOL

Drug users buying two £10 bags of heroin get a free rock of crack, which encourages 'speedballing'. Heroin purity very low (average 25 per cent)

SHEFFIELD

Crack at £10 a rock is half the price of two years ago. Standard herbal cannabis is cheaper too. Rise of 'speedballing' is a worrying trend

NOTTINGHAM

One of eight cities reporting rise in 'speedballing', in which heroin and crack cocaine are injected using the same syringe

BIRMINGHAM

Khat, a stimulant with effects like amphetamine, is increasingly popular. Misuse of anabolic steroids is becoming mainstream

IPSWICH

Price of heroin dropped by half since 2005 (now £50 a gram). Methadone and Subutex, heroin substitutes, available cheaply

CARDIFF

Most expensive cocaine in UK (£55 per gram), but the cheapest ecstasy (£1 a pill)

BRISTOL

Rising number of people suffering cocaine-related mental health problems. Skunk cannabis most expensive in UK (£140 an ounce)

LONDON

LSD still popular, along with magic mushrooms, crystal meth and MDMA. Home-grown cannabis increasingly available

LUTON

Misuse of anabolic steroids becoming mainstream, with drug services seeing big rise in number of young Asian men seeking help for misuse

GLOUCESTER

Cheapest cannabis, cocaine and crack in UK. Average heroin prices are also among the lowest in the country at £10 per 0.3g bag

PENZANCE

Heroin price fell from £60 to £40 a gram this year, attributed to Liverpool dealers. UK's cheapest herbal cannabis (£90 an ounce)

TORQUAY

Growing presence of steroids. Club bouncers using an opiate painkiller, Nubain, mixed with cocaine, to create improvised 'speedball'

PORTSMOUTH

Most expensive herbal cannabis in the UK. Cocaine among the most expensive with one gram selling for an average price of £47.50

THE NATIONAL PICTURE

HEROIN: Prices down to record low of £25 a gram. Often sold in £5 bags.

CANNABIS: Wide variations in cost - and strength - across Britain. Twice as expensive in some towns.

SPEEDBALLING: Alarming rise in injection of heroin and crack cocaine in liquid form.

ECSTASY: Price fallen to as little as 75p in some parts of country.

STEROIDS: Half of towns now report rise in mainstream misuse.

COCAINE: Price has dropped in many parts of Britain as overall misuse rises.

http://news.independent.co.uk/uk/crime/article1523145.ece