Drug seizures by the police have little impact on Britain's drug market and the millions spent on enforcement measures are unlikely to have much effect on supply on the street, a report by a team of experts said on Wednesday.

The UK Drug Policy Commission (UKDPC) said the country's drug market, said to be worth some 5.3 billion pounds, was so "highly fluid" that it was able to adapt to action by the authorities.

"We were struck by 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 and represents value for money," said one of the authors Tim McSweeney.

Britain has one of the worst drug problems in Europe in terms of the number of drug users and drug-related deaths.

The report said 380 million pounds was spent on reducing the supply of drugs in 2005/6, with the overall criminal justice costs arising from Class A narcotics, such as heroin and cocaine, estimated at more 4 billion pounds.

While seizures of Class A drugs more than doubled between 1996 and 2005, the enforcement efforts had had little effect on the availability of drugs, the commission said.

During this period, the authorities seized an estimated 12 percent of the heroin market and 9 percent of the cocaine market. But the report said between 60 and 80 percent of drugs would need to be seized to put traffickers out of business.

"By altering purity levels, traffickers and dealers are able to increase their profit margins to alleviate the effects of increased seizures and/or enforcement action," the report said.

The UKDPC said enforcement action was still important but more should be done at a local level.

It said resources should be targeted at open street-level markets, helping drug users get treatment and support and helping local communities become more resilient to drugs.

David Blakey, a UKDPC commissioner and former Chief Constable of West Mercia Police, said it was a pity that enforcement agencies were judged on their seizure rates.

"Of course drug dealers must be brought to justice, but we should recognise and encourage the wider role that the police and other law enforcement official can play in reducing the impact of drug markets on our communities," he said.