The UK now has 17 coronavirus hotspots where infection rates are above 100 per 100,000 people, new data show.
The government’s latest COVID-19 figures, released on Wednesday afternoon, demonstrate the continued spread of the more transmissible Indian variant, which has been renamed the "Delta" variant by the World Health Organization.
The statistics will prompt further doubts over Boris Johnson's plan to end England's lockdown on 21 June, though the prime minister insisted on Wednesday that this can still happen.
In the seven days up to Friday, the latest period for which figures are available, Blackburn with Darwen had the UK's highest case rate of 436.2 per 100,000.
A further 16 council areas had infection rates of more than 100 per 100,000. A full list of those areas can be viewed at the bottom of this page.
Of England's council areas, five had a case rate of more than 100 per 100,000 seven days ago. It is now 13.
Meanwhile, there were 4,330 confirmed new cases in the UK on Wednesday. Daily case numbers have been above 3,000 for the past eight days due to the spread of the Delta variant.
These data highlight why the 21 June target date for unlocking in England is in doubt.
The state of infection numbers and variants of concern are two of the government’s “four tests” when considering each stage of unlocking. Some senior advisers have this week called for the end of lockdown to be delayed.
Johnson, however, has once again repeated his "nothing in the data" mantra in another show of optimism.
“I can see nothing in the data at the moment that means we can’t go ahead with step four of the opening on 21 June," the PM said.
Watch: Boris Johnson's latest comments on 21 June unlocking target date
“But we’ve got to be so cautious because there’s no question… data on infection rates is showing an increase. We always knew that was going to happen, we always said the unlocking steps we have taken would lead to increases in infection.
“What we need to work out is to what extent the vaccination programme has protected enough of us, particularly the elderly and vulnerable, against a new surge.
“I’m afraid the data is just still ambiguous.”
He added: “The best the scientists can say at the moment in their guidance to us is 'we just need to give it a little bit longer'."
Johnson is set to make a final decision on 14 June.
On Tuesday, Scotland’s first minister Nicola Sturgeon paused plans to ease restrictions in much of the country.
And Johnson's comments were criticised by Prof Christina Pagel, a member of Independent Sage, which scrutinises government COVID policy.
She told the BBC: “I just think it’s far too early to say anything about [21 June]. And when Boris Johnson says he sees 'nothing in the data'… I don’t really know what data he’s looking at.”
Prof Pagel said cases of the Delta variant are forming the UK’s new “epidemic”. As of Thursday, there had been 6,959 cases, which was up 3,535 from 3,424 seven days before.
She said: “That’s been doubling every single week since the end of March and that was the start of the third wave.
"Just because it was masked by the decline of the other one [the Kent variant, which has been renamed 'Alpha'] doesn’t mean that we haven’t been in a situation of exponential growth – we have.”
Earlier on Wednesday, meanwhile, the COVID vaccination programme surpassed two milestones, with 75% of adults having now received a first dose in the UK and 50% having received two doses in England.
Chris Hopson, chief executive of NHS Providers, described the milestones as an “incredible achievement”.
However, he added: “We know vaccines are breaking the chain between infection rates, hospital admissions and death – but we also know two doses are better than one, particularly in our fight against the Delta variant.
“So while there’s a lot to celebrate, we’ve still got a way to go before people have had both jabs. We also know it takes three weeks for doses to be fully effective."
Here are the 17 UK areas with more than 100 coronavirus cases per 100,000 people*
Blackburn with Darwen: 436.2 cases per 100,000
East Renfrewshire: 149.7
Ribble Valley: 147.8
Glasgow City: 128.9
South Ribble: 111
Dundee City: 100.5
*figures cover the seven days up to Friday, 28 May
Watch: Do coronavirus vaccines affect fertility?