A UN report has revealed that the opium crop production in Afghanistan has increased due to warm weather and heavy rainfall, with the land used to grow opium increasing by 10% – or 201,000 hectares. Higher levels of cultivation in 2016 meant the estimated opium production spiked by 43% to 4,800 tons, according to a UN Office on Drugs and Crime (UNODC) report.

UNODC executive director Yury Fedotov said in a statement: "The survey shows a worrying reversal in efforts to combat the persistent problem of illicit drugs and their impact on development, health and security."

Increased production of opium is met with concern as it can be a source of income for terrorists and fund extremist groups. The US has previously spent $7.5bn (£6.1bn) on eradicating opium use in Afghanistan, but despite this, production of the drug has risen.

"Strong increases (in cultivation) were observed in the northern region and in Badghis province where the security situation has deteriorated since 2015," said Fedotov.

Increased opium production can have far-reaching effects. Figures from the UN in 2015 show that 246 million people used an illicit drug and of those 32.4 million people are users of pharmaceutical opium and heroin. Afghanistan's opium poppy production is responsible for more than 90% of heroin globally.

The militant group garners substantial income from the narcotics trade through offering protection to drug cartels.

"The Taliban receive large sums of money from drug traffickers because the group protects drug markets, escorts traffickers and helps them transport the opium," a Helmand resident told Deutsche Welle.

According to counter-terrorism expert Tomas Olivier, the Taliban can earn up to $300m a year from the drugs trade.

Earlier this month Fedotov made a statement in Brussels, where he announced that a $15bn fund would go towards Afghanistan in the next four years.

It is estimated that 100,000 people die a year from opium use, according to the Centre for American progress.