More than one in 20 people in Britain had Covid-19 in the last week of 2021, the highest infection rate recorded during the pandemic, official data showed Wednesday.

An estimated 3.7 million people in the UK had the virus, up from 2.3 million the previous week, as the Omicron variant surged nationwide, the Office for National Statistics (ONS) said.

The unprecedented case levels were highest in London where as many as one in 10 people had it, according to the ONS, which is seen as one of the most reliable counts as it randomly samples the population.

Across England, an estimated one in 15 people in the community were infected with coronavirus, it reported.

"#COVID19 infection rates continued to increase across all age groups in England in the week ending 31 Dec 2021, with the highest rates still seen in school age children and young adults," the ONS said.

In Scotland, Wales and Northern Ireland, where devolved governments have reimposed some restrictions in recent weeks, rates were slightly lower at between one in 20 and one in 25 people.

The statistics came as Prime Minister Boris Johnson's government announced testing rules for people in England without symptoms would be eased to help mitigate the fallout from the record infection levels.

Asymptomatic people in England who test positive will no longer require a confirmatory PCR test from January 11, the UK Health Security Agency (UKHSA) said.

Instead, those who receive a positive result on a lateral flow device will be required to self-isolate immediately, without getting the PCR confirmation.

A similar system will be rolled out in Scotland and Wales from Thursday.

 'Considerable impact'

The UK is among the worst hit countries in Europe by the pandemic, with a virus deaths of nearly 150,000 and daily case numbers crossing the 200,000 threshold in recent days.

However, Johnson has opted not to introduce tougher restrictions in England, arguing the rising levels of hospitalisations and serious illness do not yet require more measures.

He has focused instead on ramping up the vaccine booster programme which has seen nearly 60 percent of over-12s so far get a third dose.

But other UK regions have tightened anti-virus measures, with devolved governments in Edinburgh, Cardiff and Belfast all rolling out post-Christmas curbs on socialising and large events.

In Scotland, they included closing nightclubs, including on New Year's Eve, and limiting gatherings, which resulted in the top flight football league taking its winter break early.

First Minister Nicola Sturgeon said on Wednesday the measures would remain in place until at least the middle of the month.

"What is beyond doubt is that it is already having a considerable impact," she said of surging infections, noting the number of people in Scottish hospitals had risen 80 percent in the most recent week.