At least 28 children, all under the age of five, have died after drinking water from a stream contaminated with lead, Sky News reported.

The children are from the Rafi area in the west of the country, where villagers have been illegally mining for gold.

Dozens more children are ill and doctors are working to try to prevent them from suffering irreversible brain damage.

"The devastating impact of this outbreak is associated with new mining sites which are found to contain more leaded ores which are often brought home for crushing and processing," junior health minister Fidelis Nwankwo said.