Drug dealers are "extremely resilient", the report says
Police are fighting a losing battle against drugs crime, with seizures having little impact on reducing supply or demand, research has suggested.
The UK Drug Policy Commission said despite the large sums of money spent tackling the problem, traditional police tactics were not working.
It said the £5.3bn British drugs market was too "fluid" for law enforcement agencies to cut supply.
It added more should be done to reduce the effects of drugs on communities.
A Home Office spokesperson said: "The government agrees that enforcement in isolation is not effective."
Titled Tackling Drug Networks and Distribution Networks in the UK, it concluded that although the amount of Class A drugs seized between 1996 and 2005 doubled, the market had proved to be "extremely resilient".
This was despite 12% of the heroin and 9% of the cocaine in Britain being impounded during the same period, and despite the convictions of dealers and traffickers.
The independent think-tank said dealers were able to adapt quickly to interruptions in supply, for instance by reducing purity, enabling them to maintain their profit margins.
The report estimated that between 60% and 80% of drugs would need to be seized to put major traffickers out of business - yet operations on such a scale have never been achieved in the UK.
It went so far as to warn that police operations could have a negative effect on the problem.
They could threaten public safety and health by "altering the drug users' behaviour and potentially… setting up violent drug gang conflicts as police move dealers from one area to another", said our correspondent.
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Instead, the study's authors suggested the government concentrated on the "collateral damage" of the trade - sex markets, gangs, human trafficking, corruption, drug-related crime and anti-social behaviour.
The criminal justice costs of class A drugs alone are estimated at £4bn a year.
Tim McSweeney, one of the report's authors, said: "We were struck by just how little evidence there is to show that the hundreds of millions of pounds spent on UK enforcement each year has made a sustainable impact."
Former police chief constable David Blakey, of the UK Drug Policy Commission, said enforcement agencies tended to be judged by the amount they had managed to capture.
"This is a pity as it is very difficult to show that increasing drug seizures actually leads to less drug-related harm," he added.
Neil McKeganey, professor of drug misuse research at the University of Glasgow, told BBC Radio 4's Today programme the problem would be worse without the current enforcement measures.
There is no incentive at the moment for chief constables to tackle drug crime
Former deputy assistant commissioner Metropolitan Police
"The UK heroin problem, for example, is less than one per cent of the population. Many people might wonder just what it would be if drugs were able to enter the country much more easily than they do currently."
Brian Paddick, a former deputy assistant commissioner of the Metropolitan Police, told Today part of the problem was the performance targets set for police forces.
"There is no incentive at the moment for chief constables to tackle drug crime. All the performance indicators against which police forces are measured are based on reduction of acquisitive crime."
The Home Office said seizures were only part of the government's approach, with intervention programmes getting 1,000 offenders into drug treatment each week.
"Many of the report's recommendations are already being implemented," the spokesperson added.
"Our drugs strategy encompasses enforcement, prevention, education and treatment."
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