In England, around one in 640 people tested positive for Covid-19 in the week ending May 29, as opposed to just one in 1,120 the week before, the ONS said in its weekly infection survey.

Data showed that the so-called ‘B.1.617.2’ variant of the virus first detected in India – recently labelled ‘Delta’ by the World Health Organization – is likely replacing the UK variant B.1.1.7 (Alpha) as the most dominant strain.

“In the week ending May 29, 2021, we have seen an increase in cases in England that are not compatible with the UK variant B.1.1.7… these are likely to be the variant B.1.617.2… first identified in India,” the ONS said.

On Friday, the government’s Scientific Advisory Group for Emergencies said England’s virus reproduction – or ‘R’ – number had risen slightly from 1.1 to 1.2, meaning that the prevalence of Covid-19 in the population is increasing.

UK Prime Minister Boris Johnson addressed the recent rise in cases on Wednesday, telling reporters that he can “see nothing in the data” to suggest the government could not press ahead with a further easing of health measures on June 21.

He added: “But we’ve got to be so cautious because there is no question the ONS data of infection rates is showing an increase.”