London Mayor Sadiq Khan has told the government that wearing face masks while travelling the UK capital should be compulsory, the media reported.
Despite UK public health experts not currently recommending the use of face-coverings, Khan was lobbying for guidelines to be changed, reports the BBC.
The UK government's social distancing guidelines do not mention face masks.
"(But) the evidence around the world is that this is effective," the BBC quoted Khan as saying on Thursday.
"I'm lobbying our government and advisers to change their advice, and I want us to do that sooner rather than later.
"They are already reviewing this on the basis of our representation," he added.
WHO on medical masks
The World Health Organization said that it remains the case that medical masks should be reserved for healthcare workers, not the general public.
But WHO special envoy David Nabarro has suggested more widespread use of masks will become "the norm" as the world adjusts to living with COVID-19.
The overall coronavirus death toll in the UK has risen to 13,759 while the number of infections recorded so far has reached 104,148 since the outbreak began.