Al-Qaeda is in its worst financial state for years, with influence waning because of a shortage of funds, the US Treasury said yesterday.

At the same time, the Taleban in Afghanistan and Pakistan is thriving on the proceeds of poppy growing and the international drugs trade.

David Cohen, the Treasury Department’s assistant secretary for terrorist financing, said that in recent years the US had enjoyed success in cutting funding from al-Qaeda. So far this year, he said, the organisation had made four “public appeals” for money — because the US and its allies had singled out its biggest donors.

“We assess that al-Qaeda is in its weakest financial condition in several years and, as a result, its influence is waning,” he said in a speech in Washington, adding that the shortage of funds was undermining recruitment and training.

Cutting funds to al-Qaeda has been a pillar of US counter-terrorism policy since 9/11. It is, in relative terms, easier than defeating the ideology and extremism. Osama bin Laden’s organisation received much of its funding from wealthy Arab benefactors, through a network of accounts and front companies. Over the years the US has managed to expose and close many of the channels.

Analysts warn, however, that attacks are not expensive. Experts believe 9/11 cost about $500,000 (£317,000) to plan and execute, the 2004 Madrid bombings $10,000, and the July 7, 2005 London attacks just a few thousand pounds.

Mr Cohen also warned al-Qaeda still had multiple donors “ready, willing and able” to contribute and the network’s funding problems could quickly be reversed.

As President Obama considers whether to send additional troops to Afghanistan, Mr Cohen said the Taleban was in a much better financial position. Afghanistan’s booming drugs trade, fuelled by its massive poppy harvests, was a major source of funds.

The Taleban also extorted money from poppy farmers and heroin traffickers and demanded protection payments from Afghan businesses, he said.

General Stanley McChrystal, the US ground commander in Afghanistan, said in his grim assessment of the war sent to Mr Obama last month that the Taleban’s various sources of cash was a major factor in the increasingly lethal insurgency.

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