London, Dec 21 (IANS) The Taliban in Afghanistan are withholding thousands of tonnes of drugs, which they were treating like "savings accounts" so as to manipulate street prices in the west, says a US cable revealed by WikiLeaks.

The Taliban withheld 12,400 tonnes of opium from the global market to keep the price of heroin and opium at a profitable level, Antonio Maria Costa, head of the UN's office on drugs and crime, told NATO, The Guardian reported Tuesday.

Afghanistan is the world's biggest exporter of heroin and opium most of which is grown in Helmand province.

The rebels withheld opium worth around $1.25 billion. Each tonne of opium can be used to produce 100 kg of heroin.

The US cable appears to show that the UN believed that the Taliban and other insurgents in Afghanistan were well-organised, aware of the market and focused on maintaining a viable price for the drug, the media report said.

A UN spokesman declined to comment.

Costa's observations that were reported in a confidential document were expressed at a meeting held Sep 18, 2009, when he briefed NATO representatives on the results of the 2009 Afghanistan Survey, the UN's annual assessment of the drugs industry in the country.

"Costa said that Afghanistan has 12,400 tonnes of opium stocks because it produces more than the world consumes. Costa believes that the insurgency is withholding these stocks from the market and treating them like 'savings accounts'. He said the stocks pose a serious threat as it could be used to finance the insurgency. Costa encourage intelligence organisations to to keep focus on the storage and movement of Afghanistan's opium stocks.

"Costa said that even though Afghanistan was among the most impoverished countries in the world poverty was not the main factor. Costa said abandoning opium cultivation dies not produce humanitarian crisis. He said market forces caused a shift in opium prices and could easily influence farmers to grow illicit crops if high market prices and revenue could be gained from them," the cable said.

The UN's 2010 Afghanistan survey said the total 2010 opium production is estimated at 3,600 metric tonnes, which is down 48 percent from 2009. The decrease took place due to a plant infection that hit the poppy-growing provinces of Helmand and Kandahar.