Killer heroin nearly twice the purity of normal batches is being sold on the streets of Brighton and Hove.

Super-strength doses of the illegal drug are being linked to the deaths of 11 addicts in just 11 weeks since the beginning of the year.

Last night senior police officers warned users to take extra care when taking drugs to try to prevent them joining the death toll.

Altogether two women and nine men have died from drug overdoses from taking heroin that is between 60 to 70 per cent pure.

Normal heroin is about 40 to 50 per cent pure.

Four deaths happened in January, six in February and one so far this month.

The figures show an alarming four-fold rise in drug-related deaths compared with 2006 and 2007 when only three were reported in the same period each year.

Police are investigating the deaths but no arrests have been made.

Detective Chief Inspector Ian Pollard, of Sussex Police, said: "There's certainly been a significant rise in deaths.

"Initial analysis suggests that the strength of heroin available in the city is higher than normal and this may well be a contributory factor in these unfortunate deaths.

"All those who died since January were habitual drug users and were aware of the risks.

"In terms of dangers to users, the levels are worrying. It means people are putting themselves at risk of dying when they use heroin."

Police hope to stem the dramatic rise in deaths to prevent a return to the drug crisis of 2005 when Brighton and Hove was declared the drug death capital of the UK with 51 users losing their lives during the year.

A shocking report suggested that one in 50 people in the city habitually used heroin or crack cocaine.

Of that number, one in every 25 people aged 25 to 34 was receiving treatment for drug addiction.

DCI Pollard said significant work had been done since then to help addicts and jail dealers.

He said: "We have have been jointly working with partners since 2005 to ensure that the supply and demand side of the drugs market is addressed.

"Neighbourhood specialist police officers work together with crime reduction initiatives to target those drug users who are not currently in treatment and who commit crime to fund their habit.

"They are then offered fast track routes into treatment services, which are supplied by Sussex Partnership Health Trust. There is also an enforcement element that has had a significant impact on crime reduction across the city."

Since 2005 there have been 223 referrals to drug treatment programmes and police have achieved more than 295 convictions for drug possession and dealing.

In 2007 it is estimated the police recovered assets worth nearly £370,000 from dealers charged with drug trafficking offences.

Harry Schapiro, from the anti-drug charity DrugScope, said deaths from high purity heroin were not unusual because there were no controls on how they are made.

He said: "There's no quality control with illegal drugs. You can get batches that have been cut too much or haven't been cut enough.

"The heroin supply chain starts in Afghanistan. Those drugs are cut and mixed all the way down the chain until even the people selling them won't know the strength until people started dying.

"People get used to certain levels of purity. However, if suddenly you get something on the street that might be 70 to 80 per cent pure and you're not used to that level of heroin, which most people wouldn't be, the body can't tolerate it. And there's a very strong chance you will overdose on it."

Brian Oxley, the leader of Brighton and Hove City Council, said: "Obviously any death from drugs is a tragedy. Our sympathies and heartfelt concern goes out to the families of people who have lost someone to drugs.

"The community has a range of services available to help people in terms of treatment and staying away from drugs. I would encourage anyone with a problem like this to make use of everything available to get the help they need."

City councillor Bob Carden called for harsher penalties to prevent further deaths.

He said: "I'm very saddened by the news. I know of someone who lost their partner due to a drug overdose. It's a sad old business. I wish those people dealing would think of the misery they are causing to people and to their families.

"I believe we've got to be prepared to invest more getting more police on the streets to catch the dealers and penalties should be stricter."

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