Coronavirus testing is to be rolled out to employees in England who are continuing to travel to work during the lockdown, the Government has announced.
Ministers will expand the programme by offering access to lateral flow tests, which can produce results in less than 30 minutes, to businesses with more than 50 employees.
Officials said the move is part of efforts to "normalise" testing in the workplace and ensure the safety of those who cannot work from home by identifying asymptomatic carriers of Covid-19.
Only firms employing 250-plus staff previously qualified for the rapid testing regime.
Health Secretary Matt Hancock said: "To save lives and protect the NHS, we have again asked for everyone to work from home.
"But we know that for some this is not possible, which is why the workplace rapid testing programme is so important.
"Employers should regularly test their staff, and this drive across Government to raise awareness and encourage more businesses to introduce rapid testing for employees is incredibly important.
"When you consider that around one in three people have the virus without symptoms and could potentially infect people without even knowing it, it becomes clear why focusing testing on those without symptoms is so essential.
"We are already working with many employers to scale up workforce testing, spanning the food industry, retail sector, transport network, and across the public sector too.
"I strongly urge businesses and employees across the country to take up this offer of rapid testing to help stop this virus spreading further."
Frontline workers, such as police, firefighters, Border Force staff and civil servants working on the Covid-19 response, are among those who already have access to regular quick-fire tests.
NHS Test and Trace said that, as of January 29, it had provided Transport for London (TfL) staff with 2,173 tests, identifying 28 positive cases who would have otherwise continued working alongside colleagues.
According to Government statistics, 112 UK organisations have so far signed up to take part in mass testing, with employees being tested across 500 sites.
Business Secretary Kwasi Kwarteng said: "We want to be able to reopen the economy and recover our way of life as soon as it is safe to do so, and large-scale workplace testing will complement our work in getting the British people vaccinated."
