The World Health Organisation has changed its advice on face masks, saying they should be worn in public in places which have community transmission of Covid-19 to help stop its spread.
The global body said new information showed they could provide "a barrier for potentially infectious droplets".
Some countries around the world already recommend or demand the wearing of face coverings in public.
The WHO had previously argued there was not enough evidence to say that healthy people should wear masks.
Dr Maria Van Kerkhove, the WHO's technical lead expert on Covid-19, told Reuters news agency the recommendation was for people to wear a "fabric mask - that is, a non-medical mask".
The organisation had always advised that medical face masks should be worn by people who are sick and those caring for them.
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," 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.
NZ Health Ministry welcomes latest WHO advisory
New Zealand's Ministry of Health states that "there is no convincing evidence one way or other to require the use of non-medical face masks for healthy people in the community to protect them from COVID-19".
It states that there are benefits and risks to wearing non-medical face masks and countries are taking differing approaches depending on their Covid-19 status.
Non-medical masks could protect someone who is infectious with Covid-19 from spreading it to others, but they were not proven to be effective in protecting the person wearing them from becoming infected by others, the ministry said.
The WHO emphasised that masks should be part of a comprehensive strategy and that much of their updated guidance related to countries with a high degree of community transmission.
The ministry said New Zealand is increasingly confident that it has no community transmission of Covid-19 and that masks will continue to be part of New Zealand's approach to managing the coronavirus.
What are the latest key developments globally?
In the UK, the government announced on Friday that hospital visitors and outpatients would be required to wear face coverings, and that hospital staff would have to wear medical masks, even if they were not in a clinical setting.
The guidance will come into force on June 15, as more businesses open up and more pupils return to school. Also on Friday the UK became the second country to record more than 40,000 coronavirus-related deaths, after the US.
In other developments around the world:
• With more than 34,000 deaths, Brazil overtook Italy to become the country with the third-highest death toll worldwide
• The EU commissioner for home affairs said member states should reopen their internal borders by end of the month
• Portugal will start reopening its beaches today
• Meanwhile in Poland, gyms, swimming pools and amusement parks will be reopened.