Passengers will be allowed to board London’s buses for free and banned from using the front door as part of new pandemic measures announced by Transport for London (TfL).

Free travel and middle door-only boarding will be temporarily introduced from Monday to protect drivers and keep passengers safe from the coronavirus, the operator said in a statement.

Earlier this week, TfL announced that 26 members of staff across the transport network had died from Covid-19. London mayor Sadiq Khan said on Friday the total included 20 bus drivers who had lost their lives. “It breaks my heart,” he said.

“I will continue to do whatever it takes to keep our heroic transport workers as safe as possible,” said Mr Khan, who said middle-door boarding would “further protect drivers”.

He added: “I would like to remind Londoners that you shouldn’t be travelling by any mode of transport unless it is absolutely necessary, and public transport is only open for critical workers.”

Mr Khan also urged the government to change its advice to the public on wearing face masks to help combat the spread of the virus.

The London mayor told BBC Breakfast on Friday that wearing non-medical facial masks, such as a bandana, scarf or reusable mask, would add “another layer of protection” to the public.

Mr Khan, who wrote to transport secretary Grant Shapps about the issue, said he is lobbying for masks to be worn in circumstances where people cannot keep two metres apart, such as on public transport.

TfL trialled the boarding change on 140 buses across nine routes, with the operator saying it was “confident” that the low number of people travelling meant people could keep a safe distance between each other.

London bus driver on number twelve route in central London (EPA)

Limited use of London’s buses by essential workers had led the number of people travelling to “plummet” by about 85 per cent.

Bus travel in the capital normally costs £1.50 for unlimited journeys within an hour, up to a maximum of £4.50 per day.

Passengers will not need to touch in after middle-door boarding and are asked not to approach the driver. TfL has already include signage directing people away from seats near drivers, and has placed a protective film over drivers’ screens.

Pete Kavanagh, the Unite union’s London and eastern regional secretary, said the middle-door only boarding was a “very welcome move”.

He added: “We are very relieved that TfL is listening to Unite and its members. We have lost members of our bus family in recent days and we refuse to lose any more.”

Unite organised a minute’ silence at 11am on Friday in tribute to bus and transport workers in London who have died.

TfL said it was also still considering creating a “completely sealed partition” between drivers and passengers.