(Reuters) -The World Health Organization on Wednesday said a batch of cough and cold syrup sold in Cameroon under the brand name Naturcold contained extremely high levels of a toxic contaminant.

The packaging label on the syrup showed it was manufactured by a company called Fraken International (England), but the UK health regulator said no such company exists in the country, the WHO said.

"Enquiries are still underway to determine the origin of the product," WHO said, adding that the syrup may have authorizations in other countries as well.

The acceptable limit for diethylene glycol, the contaminant found in the syrup, is no more than 0.1%, according to the WHO, but the batch had syrups that contained as much as 28.6% of diethylene glycol.

The new WHO alert is the latest in a series of warnings about contaminated children's cough and paracetamol syrups.

The alert in Cameroon follows the country's health regulator saying in April that it was investigating the deaths of six children linked to Naturcold. The WHO had told Reuters it was supporting the authorities there.

Unscrupulous actors sometimes substitute propylene glycol, an ingredient used in the syrups, with cheaper but toxic alternatives like ethylene glycol and diethylene glycol, several pharmaceutical manufacturing experts told Reuters.

The contaminants can cause abdominal pain, vomiting, diarrhoea, an altered mental state and acute kidney injury, among other symptoms, which may eventually lead to death, they said.

In 2022, more than 300 children - mainly aged under five - in Gambia, Indonesia and Uzbekistan died of acute kidney injury, in deaths associated with similar products made by other manufacturers.

(Reporting by Leroy Leo in Bengaluru and Jennifer Rigby in London; Additional reporting by Bhanvi Satija in Bengaluru; Editing by Anil D'Silva, Shinjini Ganguli and Pooja Desai)