The World Health Organization has updated its COVID-19 guidelines to recommend the use of facemasks in areas where the virus is spreading and social distancing is difficult.
The WHO previously said there is no evidence to show that healthy people can prevent infection by wearing masks.
WHO Director-General Tedros Adhanom Ghebreyesus told reporters in Geneva on Friday that the update is based on evolving evidence.
He said the WHO now advises governments to encourage the general public to wear masks where there is widespread transmission and physical distancing is difficult, such as on public transport and in shops.
But he also said masks alone will not protect people from the virus, and stressed the importance of physical distancing and hand hygiene.
Globally, there have been 6.7 million confirmed coronavirus cases and nearly 400,000 deaths since the outbreak began late last year, according to data compiled by Johns Hopkins University.
The organisation said its new guidance had been prompted by studies over recent weeks. "We are advising governments to encourage that the general public wear a mask," Dr Van Kerkhove said.
At the same time, the WHO stressed that face masks were just one of a range of tools that could be used to reduce the risk of transmission - and that they should not give people a false sense of protection.
"Masks on their own will not protect you from Covid-19," said WHO Director-General Tedros Adhanom Ghebreyesus.