Adverts by two companies which made false claims about using face masks to prevent the spread of coronavirus have been banned.
The Advertising Standards Authority (ASA) ruled the claims by Easy Shopping 4 Home Ltd and Novads OU were in breach of its code.
The adverts were "misleading, irresponsible and likely to cause fear without justifiable reason", it said.
Officials have urged more hand-washing to delay the spread of the virus.
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The rulings were made against adverts by Easy Shopping 4 Home Ltd, which appeared on the Amazon website, and adverts by Novads OU for its Oxybreath Pro mask, which appeared on the Scottish Sun website via the Taboola network and other sites.
One of the Oxybreath Pro adverts stated: "It would be an understatement to say that there is a growing sense of panic.
"The best advice I've heard is to stay calm and take practical measures to protect yourself.
"One of the best ways to protect yourself is to get a high-quality face mask that can protect you from: viruses, bacteria, and other air pollutants."
The ASA said the adverts were "misleading" because the claims went against official advice.
A spokesman said Public Health England informed the ASA "that they do not recommend the use of face masks as a means of protection from coronavirus".
"We understood there was very little evidence of widespread benefit from their use outside of clinical settings," the ASA said in a statement.
They added that "prolonged use of masks was likely to reduce compliance with good universal hygiene behaviours" to help stop the spread of infectious diseases, like frequent hand-washing.
Prof Stephen Powis, NHS medical director, said: "Callous firms looking to maximise profits by pushing products that fly in the face of official advice is outright dangerous and has rightly been banned."
He called for "responsible" firms to "play their part" in tackling the outbreak, by planning how employees could work from home, encouraging hygiene measures and urging anyone with concerns to seek further information on NHS 111 online.
The number of coronavirus cases in the UK rose from 39 to 51 on Tuesday, with more than 90,000 infected globally in more than 50 countries.