A South African man has been jailed for 16 years in Afghanistan for trying to smuggle out nearly six kilograms of heroin in bottles for body-building supplements, a court said Tuesday.

The 42-year-old, whose name was not released, was arrested around September last year at Kabul International Airport and his conviction has been upheld by an appeal court, said the Criminal Justice Task Force, an anti-drugs court.

He has been sentenced to 16 years in prison and ordered to pay a fine of 1.05 million Afghanis ($21 000), it said in a statement.

He was found trying to take the heroin out of the country in bottles for body-building supplements, the force's media officer told AFP. Another man had been arrested in South Africa in connection with the case, he said.

Afghanistan is the world's leading producer of opium and heroin.

The government and its international allies are trying to end drugs production by cracking down on traffickers and persuading farmers to grow other crops.