Offices will be reshut within two weeks if coronavirus infection rates continue to rise, ministers have reportedly warned.
The new restriction would come little more than a month after Boris Johnson told people they should be returning to the workplace.
The warning was made as the national test and trace system – widely considered the best way of controlling community infection rates – appeared on the verge of collapse.
Centres across England have been overwhelmed by demand as thousands of people report having Covid-19 symptoms. Almost 4,000 positive cases were identified on Wednesday.
Government sources told The Telegraph that if the problems persisted and positive numbers continued to grow, working from home would be made mandatory where possible for the first time since the national lockdown in the spring.
Business leaders have already said it would be impossible to keep people in offices without an effective testing scheme.
Matthew Fell, chief policy director of the Confederation of British Industry, said: "If we are to successfully encourage more people into their workplace safely, then the test and trace system will be a key component.
"Reports of people being unable to access tests in their area or waiting too long to get the results will be deeply frustrating for individuals and businesses alike.
“No one doubts how much effort is going in to get it right. The prize is having a faster turnaround in getting results which will let people know where they stand and whether they need to self-isolate or can return to work quickly."
Adam Marshall, director general of the British Chambers of Commerce, echoed the comments.
He said: "A truly comprehensive test and trace programme is essential if the UK is to manage the virus without further lockdowns, which will cripple businesses.
"Continuing delays and a shortage of tests saps business, staff and consumer confidence at a fragile moment for the economy."
Meanwhile, many schools are already planning how they could transform their teaching into a hybrid format with pupils in classes some days and working from home others.