Afghan troops seized drugs worth $26 million during an anti-drug operation in Afghanistan's Nangarhar province, the command of Afghan Special Forces said on Wednesday.

"Afghan Special Forces and counter-narcotics police of Afghanistan carried out an operation in Khogyani district of Nangarhar province on Monday night, seizing a large amount of narcotics and drugs," it said in a statement.

Among the drugs were 8,000 kg heroin, 500 litres of liquid heroin, 230 kg of ammonium chloride and a big amount of chemical elements, Xinhua news agency reported.

The restive Nangarhar province with Jalalabad city as its capital, has been the scene of heavy clashes between security forces, Taliban militants and Islamic State (IS) fighters over the past years.

The seizure of the drugs was a heavy blow for insurgents and anti-government militants as they have been using profits from the illegal trade in drugs to fund insurgency, the statement added.

Much of the world's opium poppy is cultivated in the militancy-hit country.

In 2016, some 4,800 tonnes of opium was produced in Afghanistan, particularly in western and southern parts of the country, where the government security forces have little presence, according to official figures.