Parents of the affected children were being interviewed and an epidemiological survey was under way, he added.

'Great loss'

Yusuf Sarki Muhammad, a journalist in Nigeria, told Al Jazeera: "The government has mounted a huge campaign to enlighten the citizens on the danger caused by this drug, but there is also this problem of illiteracy on the part of Nigerians.
 
"Quite a number of people here do not know how to read and write - a lot of people do not even know what is on the media."

Health officials said it was unclear if the death toll would rise as they did not know how many bottles of the mixture were still in circulation or whether any had been exported.

"The death of any Nigerian child is a great loss to the nation," Babatunde Oshotimehin, the health minister said in a statement.

"The federal ministry of health sincerely regrets this painful incidence and sympathizes with the nation and the families."

Deadly risk

Many bottles of the paracetemol-based formula were found to have a high concentration of diethylene glycol, which is sometimes used illegally as a cheaper alternative to glycerin, which thickens syrups and toothpaste.

Exposure can cause kidney and liver damage and may be fatal.

The first cases were recorded in November and health officials said in December that at least 24 children had died.

More than 400 bottles of My Pikin syrup have been recovered from markets and pharmacies and several officials from Barewa Pharmaceuticals, the manufacturer, have been arrested. 

The Lagos-based company, which has been closed down, said it had been told it was purchasing propylene glycol, a normal ingredient in the teething formula.