COVID cases have risen for the first time in two months, according to the latest figures.
The spike is likely to be caused by increases in cases compatible with the original Omicron variant BA.1 and the newer variants BA.4 and BA.5, the Office for National Statistics (ONS) said.
A total of 989,800 people in private households are estimated to have had the virus last week - up from 953,900 the previous week.
It is the first time total infections have risen week-on-week since the end of March, when the number hit a record 4.9 million at the peak of the Omicron BA.2 wave.
Infections rise in all four nations
All four nations have seen a rise in infections, though the ONS describes the trend in Scotland and Wales as "uncertain".
The ONS tweeted on Friday that an estimated one in 70 people (not including hospitals, care homes or communal establishments) in England had COVID up to 2 June this year - equating to 797,500.
The data, obtained from the COVID Infection Survey, found one in 40 (124,100) in Scotland were likely to have the virus last week - up from 105,900 or one in 50.
In Wales, one in 75 people are estimated to have tested positive, the equivalent of 40,500 - a slight increase from 39,600.
Infections in Northern Ireland have risen for the second week in a row to 27,700 people or one in 65 - up from 24,300 which works out to one in 75.
"Across all four UK countries, the percentage of people testing positive for COVID-19 compatible with Omicron variants BA.1, BA.4 and BA.5 increased in the week ending June 2 2022," the ONS said.
Positive cases have increased in people aged 35 to 49 - with early signs of an increase in Year 12 school pupils ranging up to 24-year-olds.
The percentage of people testing positive dropped in people aged 50 to 69 and over 70s in the fortnight leading up to 2 June.
Omicron BA.1 is the original variant of Omicron that saw infections surge across the UK around in December and early January this year.
Newer variants could become dominant
Newer variants, BA.4 and BA.5, were recently classified as "variants of concern" by the UK Health Security Agency (UKHSA).
Scientific analysis found the strains are likely to have a "growth advantage" over BA.2, which remains the dominant strain.
Initial research indicates BA.4 and BA.5 variants have a degree of "immune escape" - meaning the immune system can no longer recognise or fight the virus.
This is likely to contribute to their dominance over BA.2, the UKHSA said.
Rising hospital admissions
In England 4,082 patients had COVID on Thursday, 9 June - up 6% on the previous week.
And in Scotland, 637 cases were recorded on 5 June, the latest date available, showing a week-on-week rise of 8%.
Patient numbers had steadily decreased since early April after the peak of the Omicron BA.2 wave.
The figures for people in hospital with the virus in Wales and Northern Ireland have levelled off in recent days.
Hospital admissions are highest among people aged 85 and over, the UKHSA tweeted on Friday.
Dr Jamie Lopez Bernal, UKHSA consultant epidemiologist for immunisations and countermeasures, said: "Recent data has shown a small rise in positivity rates and hospitalisations with COVID.
"These small increases should be interpreted with caution as data may be subject to delays due to the Jubilee bank holiday."