The Taliban's supreme leader on Sunday ordered a ban on poppy cultivation in Afghanistan, with a warning that the hardline government would crack down on farmers planting the crop.
Afghanistan is the world's biggest producer of poppies, the source of sap that is refined into heroin, and its production and exports have boomed in recent years.
"All Afghans are informed that from now on cultivation of poppy has been strictly prohibited across the country," said a decree issued by Supreme Leader Hibatullah Akhundzada.
The decree was read out by government spokesman Zabihullah Mujahid at a gathering of reporters, foreign diplomats and Taliban officials.
"If anyone violates the decree the crop will be destroyed immediately and the violator will be treated according to the Sharia," it said.
The order said the production, use or transportation of other narcotics was also banned.
It is not the first time the Taliban have outlawed the poppy trade. Production was banned in 2000 before the group was overthrown by US-led forces after the 9/11 attacks.
During their 20-year insurgency against foreign forces, the Taliban heavily taxed farmers cultivating the crop in areas under their control.
It became a vital resource for the group to generate funds.
The United States and Nato forces tried to curb poppy cultivation during their two decades in Afghanistan by paying farmers to grow alternative crops such as wheat or saffron.
But their attempts were thwarted by the Taliban who controlled the main poppy-growing regions and derived hundreds of millions of dollars from the trade, experts say.
Deputy Prime Minister Abdul Salam Hanafi rejected claims that the Taliban helped to fuel poppy cultivation during their insurgency.
"How come it was exported all over the world when they [US-led forces] had full control over Afghanistan?" Mr Hanafi said on Sunday.
Afghan media reports say production increased in two southern provinces, Kandahar and Helmand, since the Taliban seized power in August, although data is not available.
Afghanistan has a near monopoly on opium and heroin, accounting for 80 to 90 per cent of global output, the United Nations Office on Drugs and Crime has suggested.
The area under poppy cultivation hit a record high in 2017 and has averaged about 250,000 hectares in recent years, roughly four times the level of the mid-1990s, UN figures indicate.
A farmer in Helmand said poppy prices had already more than doubled in recent weeks after rumours that the Taliban would ban cultivation. But he said he needed to grow poppies to support his family.
"Other crops are just not profitable," he told Reuters, speaking on condition of anonymity.