The World Health Organisation says it supports government initiatives that require or encourage the public wearing of masks, marking a major shift from previous advice amid the Covid-19 pandemic.
The WHO added that surgical masks should be reserved for medical professionals, while the public should use mainly cloth or home-made face coverings.
The updated stance comes as more scientific research points to the positive effect of wearing masks in preventing the spread of the coronavirus, with more governments in Europe requiring people to cover their noses and mouths in public.
"We can certainly see circumstances on which the use of masks, both home-made and cloth masks, at the community level may help with an overall comprehensive response to this disease," Dr Michael Ryan, executive director of the WHO's health emergencies programme, said on Friday.
"There may be situations where the wearing of masks may reduce the rate at which infected individuals may infect others," Ryan said. "We will support governments who wish to have a measured approach to the use of masks and who include that as part of the comprehensive strategy to control this disease."
By comprehensive strategy, the WHO means measures such as encouraging washing of hands, physical distancing and rapid testing to identify and quarantine those who are infected.
The WHO has long been concerned about encouraging the use of masks, as that could result in stockpiling of the already limited supply.
"Surgical and medical masks and masks like N95 are for the medical systems and we must prioritise their use for the front line," Ryan said, adding that a group of experts are assessing the use of masks and will look at every single research paper.
Previously the WHO advised that only individuals with symptoms or those taking care of at-risk people should use masks.
The wearing of masks began in Asia early in the crisis. Many Asian countries endured the Sars outbreak in 2003, when it was common for people to wear masks in public.
Only in the last week or so did Austria, Slovakia and the Czech Republic introduce public requirements for people to wear masks in places such as supermarkets.
California on Wednesday became the first US state to offer official guidelines acknowledging that wearing a mask could help contain the spread of coronavirus, and other states and municipalities have since done the same.
On Friday, a group of University of Hong Kong researchers published an article in Nature saying that their research indicated that surgical masks could prevent transmission of human coronaviruses and influenza viruses from symptomatic people.
This article was first published in South China Morning Post.