"London is at a very worrying tipping point right now," said London Mayor Sadiq Khan.
"It's vital that testing capacity is increased immediately in London and focused in the areas it is needed most. Any delay will mean letting the city down and will cost lives," he said.
London's coronavirus watch comes in as several other regions such as Cardiff, Swansea county areas and the town of Llanelli in Wales came under stricter lockdown restrictions.
The lockdowns for Cardiff and Swansea mean that around 50 per cent of the Welsh population will be subject to local lockdowns by the end of the weekend.
Households in Leeds are also set for a ban on people meeting in private homes or gardens, bringing it in line with rules in Bradford, Kirklees and Calderdale and several other areas in northern England.
The clampdown comes as figures show a "widespread growth of the epidemic across the country" of between 4 and 8 per cent per day.
According to the Office for National Statistics (ONS), coronavirus cases in England have risen by 60 per cent in the past week. A random survey estimated there were 9,600 new cases a day in England in the week to 19 September, three times that being picked up by general testing. This represents an increase from 6,000 a day, when matched with the same survey conducted the previous week.
The ONS said there was "clear evidence" of an increase in the number of people testing positive for COVID-19 in all age groups across the country, but rates are currently highest in those aged 17-24.
It found that infection rates are highest across the north of England and in London, with smaller increases seen in the Midlands region of England.
It comes at the end of a week which saw a range of curbs and curfews announced by UK Prime Minister Boris Johnson, including widening the legal requirements for face coverings and earlier closing times for pubs, bars and restaurants.
In his address to Parliament, he warned that the UK is at a perilous point in its strategy to fight the pandemic and the tougher measures are likely to remain in place for around six months.
(Only the headline and picture of this report may have been reworked by the Business Standard staff; the rest of the content is auto-generated from a syndicated feed.)
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