Public Health England (PHE) has warned parents not to buy face coverings for babies and young children due to the risk of choking and suffocation.
It made the move after becoming aware that masks and coverings are being sold in shops and online aimed at youngsters.
Professor Viv Bennett, chief nurse at the agency, said: “PHE has been made aware that face coverings for babies and very young children are available for sale in England.
“Guidance is clear that children under the age of three years should not wear face coverings or masks.
“These masks should not be used as they are potentially dangerous and can cause choking and suffocation.
“If you or your child is unwell with the symptoms of Covid-19, then you should get a test and stay at home until you get the result.
“If you are worried then you should call 111 or speak to your doctor.”
Face masks become compulsory in supermarkets and shops in England on Friday.
But children aged under 11 are exempt.