LONDON (Reuters) - With Britain in lockdown, supermarkets have started to limit the number of customers in stores at any one time to enforce social distancing during the coronavirus outbreak.

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Prime Minister Boris Johnson on Monday ordered Britons to stay at home to halt the spread of the virus, imposing curbs on everyday life without precedent in peacetime. But people are still allowed to leave their homes to shop for basic necessities.

Waitrose was the first chain to say on Tuesday its supermarkets and convenience shops would begin to limit customer numbers. It said limits would be specific to each branch based on the number of tills.

“Shop managers will use their judgment on customer numbers and when the shop is at capacity to manage social distancing will operate a one in, one out policy,” Waitrose said.

Waitrose, part of the John Lewis Partnership [JLPLC.UL], is also using “marshals” to help manage queues outside shops and if necessary remind customers to respect the government’s social distancing rule requiring people to keep at least two metres apart from each other.

Outside Waitrose stores there will be signage and a coned area instructing customers where to queue.

Asda, Britain’s No. 3 supermarket group, said it was also limiting the number of customers in its stores, when necessary.

Sainsbury’s, the No. 4 player, and Morrisons are doing similar.

“We have signs about social distancing in the store and on those signs it does say we might from time to time limit the number of people that actually come in,” said a Morrisons spokesman.

Market leader Tesco had no immediate comment on its plans.

On Monday, Morrisons installed large perspex screens at all checkouts in all of its stores to shield customers and checkout staff from each other, while discounter Aldi has started to install them.

Waitrose, Asda and discounter Lidl also plan to install clear screens and Waitrose has ordered special protective visors for its staff.

All supermarkets are asking customers to pay with card rather than cash at tills as a way to help contain the spread of the virus, which has killed 422 people in Britain and infected 8,077.

Britain is raising the spending limit for contactless card payments to 45 pounds ($52) from 30 pounds on April 1 to reduce the need for physical contact with devices, the UK Finance industry association said.

The pandemic has resulted in an unprecedented increase in demand for food and household products, forcing supermarket staff to work round the clock to keep shelves stocked.

Aldi said on Tuesday it was paying its store and distribution staff a 10% bonus on hours worked, effective from March 9, mirroring a similar announcement from Tesco on Friday.