Opium poppy cultivation in Afghanistan has reached a record high this year, a UN report has revealed, highlighting the failure of the US-led campaign to crack down on the lucrative crop.

The total area under cultivation was about 224,000 hectares (553,500 acres) in 2014, a seven percent increase on last year, according to the Afghanistan Opium Survey released by the UN Office on Drugs and Crime.

Just 74,000 hectares was being used to grow poppies in 2002, a year after the Taliban regime was toppled.

The survey said that potential opium production was estimated at 6,400 tonnes in 2014, a rapid increase of 17 percent from 2013, but not as high as the record 7,400 tonnes produced in 2007.

"The country is having to stand on its own feet [and] ... will have to deal with this criminalisation of its economics and politics as a matter of priority," Jean-Luc Lemahieu, director of policy analysis at UNODC, said.

The UN survey said the "farm-gate" value of opium in Afghanistan was about $0.85bn - four percent of the country's GDP - while just 2,692 hectares of poppy fields were eradicated in 2014 - a 63 percent drop from the previous year.

Despite a decade of costly US and international counter-narcotics programmes, poppy farming has expanded in the south and west regions, which include the most volatile parts of the country where the Taliban insurgency is the strongest.

Heroin addiction

Poppy farmers are often taxed by the Taliban, who use the cash to help fund their fight against government and NATO forces.

"Most of the areas in which we were fighting cultivation was under enemy control. This affected our plans very badly," Mubariz Rashidi, acting minister of counter narcotics, said.

"The security forces that should have destroyed the poppy fields were busy providing security for the presidential elections. With opium, Afghanistan cannot go towards progress, prosperity and development."

Afghanistan grows about 80 percent of the world's opium, which is used to produce highly addictive heroin.

About 12,500 NATO troops will remain into 2015, but the force's 13-year combat mission against the Taliban will finish at the end of this year.

The poppies, which provide huge profits in one of the world's poorest countries, play a large part in the corruption that plagues Afghan life at every level.

President Ashraf Ghani, who came to power in September, has pledged to tackle corruption as he seeks to steer his strife-torn and impoverished country into a new era after the rule of Hamid Karzai, president since 2001.

Heroin addiction levels in Afghanistan have also risen sharply - from almost nothing under the 1996-2001 Taliban regime, to more than one million heroin addicts today, according to UN figures.