Image copyright Getty Images Image caption Helmand province is Afghanistan's largest opium producer

The opium-growing area around Britain's main base in Afghanistan nearly quadrupled between 2011 and 2013, the UK government has said.

Poppy fields took up 19,136 hectares (47,286 acres) in the district nearest Camp Bastion in Helmand province last year.

That compares with a figure of 5,413 hectares (13,376 acres) in 2011.

The Foreign Office said it would take "a generation of effort and Afghan will" to reduce opium production.

Poverty

Britain does not collect statistics on production of opium, but it helps fund the United Nations Office for Drugs and Crime which produced the figures.

Helmand is the largest opium-producing province in Afghanistan. The figures, revealed in a parliamentary answer, cover the Nad Ali district.

Foreign Office minister Hugh Robertson admitted the international community had misjudged its ability to tackle the heroin trade in Afghanistan.

He said many communities in the area relied on opium cultivation to survive because of poverty and insecurity.

Mr Robertson added: "Helmand is particularly susceptible to this problem due to its relatively porous border with Pakistan which is exploited by smugglers, and its history of opium production."

British troops are in the process of withdrawing from Afghanistan. Military forces and Foreign Office staff are due to leave the country by the end of 2014, with the only remaining British presence at a military academy in Kabul.