The NHS’s supply of face masks could be jeopardised if the Government begins advising the public to wear them, hospital bosses have warned.

Scientific advisers for the Government are carrying out a review of the use of face masks, despite the World Health Organisation (WHO) saying there is no evidence to support their use by the general population.

Earlier this month, researchers at the University of East Anglia (UEA) found that wearing face masks could help protect people – but stressed that “the evidence was too uncertain to support the widespread use of face masks as a protective measure against Covid-19”.

Chris Hopson, chief executive of NHS Providers, which represents hospitals and NHS trusts in England, has urged the Government to “fully assess” the impact any new advice could have on health service supplies.

He said: “Fluid repellent masks for health and care staff are key to safety and to avoid the spread of coronavirus.

“Securing the supply of masks, when there is huge global demand, is crucial. This must be a key consideration for Government.

“There needs to be clear evidence that wearing masks, along with other measures, will deliver significant enough benefits to take us out of lockdown to potentially jeopardise NHS mask supply.”

WHO guidance issued earlier this month acknowledged that the virus could be passed on by people who are not yet symptomatic, but it said: “Current evidence suggests that most disease is transmitted by symptomatic, laboratory confirmed cases.

“There is currently no evidence that wearing a mask (whether medical or other types) by healthy persons in the wider community setting, including universal community masking, can prevent them from infection with respiratory viruses.”

It warned that the use of masks by the public can create a “false sense of security” and lead to people ignoring other protective measures, such as hand hygiene and physical distancing.

Masks can even be a source of infection when not used correctly, the WHO added.

Prof Babak Javid, consultant in infectious diseases at Cambridge University Hospitals, told the PA news agency that “population mask wearing should be an important part of the response to Covid”.

He added: “Once Covid cases are largely suppressed, we can stop wearing masks, their incremental gain will be low. But now, to really benefit from masks, the majority of us need to wear masks.”

Professor Jackie Cassell, deputy dean at Brighton and Sussex Medical School, added: “It’s a balance - masks can protect, but they can also carry virus from one person to another. Putting a mask on and off involves touching your face.

“If you put a clean mask on your face before leaving home that may reduce your risk of breathing in virus particles on public transport, for example. Also, if you have Covid today but no symptoms, and you cough, you will be less likely to transmit it to someone else.

“On the other hand if you are wearing a mask, and adjust it while shopping, you may transfer virus onto the mask and your face from what you have touched. In this case the mask can act as a ‘fomite’ which transfers virus from one person to another.

“You need to be very careful taking your mask off, and disposing of it or putting it in the washing machine. It’s still essential to wash your hands before going out, when you get to work or back home. Make sure you don’t touch a used mask after washing your hands.”