People are being warned to watch out for false guidance about coronavirus online amid attempts by tech giants to tackle misinformation.
The Department of Health and Social Care said anonymous posts being shared that claim to be from Stanford Hospital or Japanese doctors who recommend self-testing for Covid-19 by holding their breath are not accurate.
It pointed towards nhs.uk/coronavirus for official advice on the outbreak.
“We’re aware of inaccurate advice circulating on #COVID19,” the department tweeted.
“Anonymous posts, claiming to be from Stanford Hospital or Japanese doctors, are suggesting you can self-check for #coronavirus by holding your breath.
“This is not accurate.”
It comes as a cross-Government counter-disinformation unit was set up in a bid to deal with the potential extent, scope and impact of misleading and false details.
The Department for Digital, Culture, Media and Sport-led team will engage with social media companies to monitor interference with the aim of limiting the spread coronavirus-related fake news.
Official NHS guidance is now being displayed at the top of internet search results as part of a crackdown.
It comes after a fake account posing as a hospital was suspended on Twitter for posting inaccurate information about coronavirus cases.
The account, claiming to be a hospital in Andover, Hampshire, falsely posted it had received a number of patients with coronavirus-like symptoms before it was suspended by Twitter.
Facebook has also stepped up its efforts, temporarily banning adverts and listings selling medical face masks, as well as addressing posts that promote fake cures, such as false suggestions drinking bleach is a solution.
Earlier this month, the Prime Minister said social media has a “very important role” in preventing conspiracy theories being shared online.
On Wednesday, tech companies including Facebook, Google, Amazon, Microsoft and Apple were invited to Downing Street to discuss how they can help.