UK Prime Minister Boris Johnson said he aimed to get the country "moving closer to a sense of normality" as children returned to school on Monday after a two-month closure.

As part of the plan, millions of high school and college students coming back to UK classrooms will be tested for the first few weeks.

Authorities want to quickly detect and isolate asymptomatic cases in order to avoid sending entire schools home.

"We are being cautious in our approach so that we do not undo the progress we have made so far," Johnson said as he urged people to get vaccinated.

High schools and colleges could reopen in phases to allow for testing.

The UK government has distributed nearly 57 million rapid "lateral flow" test kits to schools across the country but there are concerns about the accuracy of the tests, which may result in pupils being forced to self-isolate unnecessarily.

But Susan Hopkins, a director at Public Health England, told the BBC that evidence from testing over the past eight weeks suggested less than one in 1000 tests resulted in a false positive.

Meanwhile, Sri Lanka's government has ended a year-long work-from-home program for public employees due to the pandemic.

Employees were ordered to report back to their workplaces starting on Monday in order to ensure the uninterrupted delivery of public services.

At the start of the pandemic last year, the government imposed a lockdown across the island country for more than a month and temporarily closed some government departments.

As a precaution, a limited number of employees were allowed to go to work while in some institutions employees had been permitted to work from home since last April.

A South Korean province near the capital of Seoul has ordered local business owners and farmers to have all foreign employees tested for the coronavirus in the next 15 days, targeting tens of thousands of workers.

The mass testing campaign is the most significant step South Korean officials have taken yet to stem transmissions among migrant labourers, who often face harsh working and living conditions that health authorities say make them more vulnerable to infections.

The order issued on Monday by Gyeonggi province Governor Lee Jae-myung covers at least 85,000 legally hired migrant workers, with fines up to 3 million won ($A3,390) for non-compliant employers.

The order also requires employees to ensure their undocumented workers get tested too.

The province has encouraged these workers to come forward, saying they won't be reported to immigration authorities if they are tested before March 22.

South Korea has confirmed more than 92,000 virus cases, including 1642 deaths.

Australian Associated Press