Sadiq Khan refused to rule out making London Underground cashless, telling Mayor's Question Time "these things are kept under review."
Mr Khan was asked by Liberal Democrat Assembly Member Caroline Pigeon if he would let the Tube phase out cash in favour of card payments for passengers.
"I think it would be irresponsible after twelve months of a pandemic where the virus spreads by touching to rule out anything for the future," Mr Khan responded.
Transport for London said a large number of ticket machines were converted to card only at the start of the pandemic to avoid staff handling coins. It's unclear if the move will become permanent.
200 of the 270 Underground stations are currently cashless
London buses and trams went cashless some time ago
TfL is currently conducting a 'review' about whether to make the Tube permanently cashless
During lockdown numbers travelling on London's transport network plummeted as the government repeated its 'Stay At Home' message.
Widespread working from home has been one of the biggest changes in behaviour during the pandemic, with scores of offices in London still empty.