Afghan investigators say they have found no evidence that poppy fields in the south of the country were sprayed with toxic chemicals from the air.

Investigators were sent to Helmand province, after farmers in four villages complained of skin troubles following the alleged spraying. They said a plant disease was to blame for the skin trouble.

The deputy interior minister for drugs, General Mohammed Daud, described the allegations as "propaganda spread by enemies of Afghanistan in an attempt to alienate farmers from the government."

The U.S.-led coalition in Afghanistan - which controls the country's air space - had denied any involvement in the alleged spraying.

In November, the Afghan government began an inconclusive probe into similar claims that unidentified foreign troops had sprayed fields in eastern Nangarhar province.

Some information for this report provided by AP and Reuters.