The Taliban have earned up to $470 million US from the Afghan opium trade this year alone, money that is being used to finance the insurgency against international and Afghan forces, the United Nations said on Thursday.

As well as the income earned from directly taxing farmers' output and from levies on opium processing and on trafficking the drug, there is evidence the Taliban are hoarding opium stocks to prop up prices, the UN said in a report.

This suggests the Taliban may not be overly worried in the short term by U.S-led efforts to eradicate poppy fields, because lower supply may end up lifting prices, potentially allowing the militant movement to increase its earnings.

"Despite the drop in opium cultivation, production and prices, the Taliban and other anti-government forces are making massive amounts of money from the drug business," the UN's office on drugs and crime said in its 2008 Afghan opium survey.

This revenue boost comes at a time when the Taliban are stepping up attacks throughout Afghanistan, especially in the south and east, across the border from Pakistan, where the U.S. military says al-Qaeda and Taliban cells are now based.

Drug profits aid Taliban resiliency

The UN report estimated the Taliban earned $50-$70 million from imposing a 10 per cent charge, called ushr, on economic activities such as opium farming this year, as well as $200-$400 million from levies on opium processing and heroin trafficking.

"With so much drug-related revenue, it is not surprising that the insurgents' war machine has proved so resilient, despite the heavy pounding by Afghan and allied forces," Antonio Maria Costa, UNODC executive director, said in the report.

It's the first time the UN has put such a high figure on the Taliban's revenue stream, but the total does not include money the Taliban are believed to be making from exports of cannabis, another widely produced Afghan crop.

In its report, the UN said opium poppy production — the raw material for heroin that is exported to Europe, the Middle East and the United States — had actually fallen substantially in 2008 following a U.S. and Afghan government crackdown.

As a result of that revenue decline, and the fall in international prices, Costa said there was evidence the Taliban and its associates were hoarding opium stocks in order to manipulate market prices.

With files from Reuters