Washington - Opium production in Afghanistan has fallen 31 per cent this year, White House drug czar John Walters told reporters on Friday.

Walters, director of the Office of National Drug Control Policy, said 5,500 tons of opium were produced in Afghanistan this year, down from 8,000 tons in 2007. In 18 of the country's 34 provinces poppy production has been stopped, thanks in part to stepped up efforts by the Afghan government and US and allied troops, he said.

The United Nations, however, said in an August report that poppy production has fallen just 6 per cent.

Efforts to halt drug production have been concentrated in Afghanistan's south-west, where 90 per cent of poppy production occurs, but have been complicated by the fact that so many people rely on the drug trade for income, he said.

The US will continue its "aggressive policies" against opium production, Walters said.

Afghanistan is the world's largest producer of the drug. (dpa)