Boris Johnson has warned up to 30 places in Britain are at risk of "tough local lockdowns" as coronavirus cases continue to rise.
The Prime Minister said other areas could follow Leicester in imposing local restrictions to prevent a second spike of Covid-19.
Mr Johnson told Sky News : "There are between ten and 30 places where you are seeing it bubbling up a little bit.
"I think the country as a whole understands that the best way to deal with this is if we have tough local lockdowns to get it under control in those towns."
After praising Leicester's "huge effort" in reacting to the first local lockdown in Britain, Mr Johnson warned the country cannot get complacent, adding it would be wrong to assume "somehow we're out of the woods."
"It is absolutely vital that as a country we continue to keep our focus and our discipline and that we don't delude ourselves that somehow we're out of the woods or that this is all over, because it isn't all over," he added.
But Mr Johnson defended the way the government has handled the country's response to the pandemic, which has seen nearly 46,000 lives lost from the virus.
Speaking on a visit to North Yorkshire, he said there has been "a massive success now in reducing the numbers of those tragic deaths".
It comes after the PM warned a second wave of the virus could hit within two weeks.
A Downing Street source told the Mail: "The PM is extremely concerned by what he's seeing abroad and fears we could be seeing the same thing here in a fortnight.
"People have got to realise we are still in the middle of a pandemic.
"He wants to go further on opening things up and getting people back to work, but he knows it'll be his head on the block if things go wrong."
Worrying data shows the number of new Covid-19 infections has risen sharply as ministers fret over fears of a second spike.
Towns including Oldham, Rochdale, Blackburn with Darwen and Luton have been battling spikes, as has the city of Bradford.
The Department for Health and Social Care revealed that 846 people tested positive in the 24 hours to 9am this morning - up from 763 yesterday.
On Tuesday, 581 cases were identified.
The daily death toll in the UK rose by 38, with the overall number now at 45,999.
Scientists at Cambridge University have said it is "very likely" that most regions in England are close to the point at which the virus begins to spread exponentially.
The data from the Cambridge MRC Biostatistics Unit found that four out of seven English regions have seen a rise in infections in recent weeks.
The south-east and the south-west now have an R rate above 1, meaning the infection is spreading in these areas.
Figures from the Department of Health reported by the Mirror show the number of cases in areas such as Hyndburn, Hackney and Swindon have soared.
Hyndburn cases rose from six to 54 in the last two weeks, while Swindon saw a rise of 23 to 56.
In Birmingham the number of cases soared from 130 to 295, while in Blackburn and Darwen cases jumped from 107 to 242.
Elsewhere, Chief Medical Officers have today confirmed an immediate change to self-isolation rules for anyone experiencing systems - extending the time to 10 days from the previous minimum of seven days.
People can be "released" from isolation earlier than 10 days if a Covid-19 test comes back negative.
However, if symptoms persist, patients need to stay at home for longer than 10 days until they recover.
Top 10 places where cases have grown in the last two weeks
Hyndburn : From 6 to 54 - growth rate of 9
Eden : From 4 to 33 - growth rate of 8.25
Sandwell : From 40 to 163 - growth rate of 4.08
Hackney : From 30 to 90 - growth rate of 3
Trafford : From 33 to 99 - growth rate of 3
Swindon : From 23 to 56 - growth rate of 2.43
Birmingham : From 130 to 295 - growth rate of 2.27
Blackburn with Darwen : From 107 to 242 - growth rate of 2.26
Barnet : From 23 to 49 - growth rate of 2.13
Walsall : From 28 to 58 - growth rate of 2.07
