Cultivation and production has declined since 2007, when the all-time record of 8,200 tonnes was recorded. Opium production fell six percent and cultivation declined 19 percent in 2008.

Taliban militants, who ruled Afghanistan for six years, banned the crop and introduced the death penalty for opium growers in July 2000, more than a year before their regime was toppled by a US-led military invasion. The move was widely seen by the militants to help boost the prices for opium, which was lower than previous years due to large stockpiles.

Wednesday's UN report could be small solace for the Western-backed Kabul regime amid an upsurge in insurgent attacks and political limbo caused by the controversial Aug 20 presidential elections, the official results of which have yet to be announced.

The partial election results showed President Hamid Karzai ahead of his nearest rival, Abdullah Abdullah, by more than 12 percent, but mounting allegations of fraud and intimidation of voters threaten to undermine the election, the second in the history of Afghanistan.

Major candidates including Abdullah, who repeatedly accused Karzai of running a 'narco-state' during the campaign, have warned that they would not accept the outcome, while their supporters threatened to resort to street violence if the election is stolen by fraud.

Costa said opium eradication by Afghan forces supported by international troops 'continues to be a failure,' as only less than four percent of the planted areas have been eradicated in the past two years.

He urged the government and international community to provide greater support to Afghan farmers to find an alternative, while insisting that 'drug lords should be brought to justice'.

'In post-election Afghanistan, the rural development push must be as robust as the current military offensive - to feed and employ farmers, not just to search and destroy their drugs,' he added.