The World Health Organization (WHO) was alarmed by the appearance of life-threateningly contaminated cough syrups for small children.

A WHO spokeswoman said on Tuesday in Geneva that it was unclear whether it was counterfeit medicines or juices that were accidentally contaminated during production.

Industrial solvents or antifreeze have been detected in the juices at levels that can be lethal to young children.

The WHO called on authorities around the world to be vigilant and controlled on Monday evening.

"We depend on governments and regulators to look at how the toxic substances got into the supply chain and what needs to be done to stop it," the WHO spokeswoman said on Tuesday.

"Accidents can happen, but they shouldn't happen."

According to the WHO, more than 300 small children in Gambia, Indonesia and Uzbekistan have died in the past few months after ingesting such juices.

At least seven countries reported confirmed and suspected cases of contaminated cough syrup, including the Philippines, East Timor, Senegal and Cambodia.

In three cases, the WHO issued product warnings.

In Gambia, the cough syrups were from Maiden Pharmaceuticals Limited from Haryana in India, in Indonesia from local manufacturer PT Afi Farma and in Uzbekistan from Marion Biotech Pvt Limited from Uttar Pradesh in India.