"The threat this virus poses to our city is at crisis point", Khan said in a statement on Friday. And almost 500 people have died in London hospitals because of COVID-19 complications in the past three days.
He told BBC Radio 4's Today: 'This is the challenge with the Covid pandemic and why we have been asking the population to really reduce mixing, to stay at home, to reduce the number of Covid infections because of the knock-on impact of this disease. "If we do not take immediate action now, our NHS could be overwhelmed and more people will die". Also on Friday, the United Kingdom registered 1,325 fatalities.
There are 32,294 coronavirus patients in United Kingdom hospitals on Friday across all words, including intensive care units - more than 50 per cent higher than the peak of the first wave in spring.
England, much of Scotland, Wales and Northern Ireland continue to be under strict national measures, with stay-at-home orders in place for most people.
Khan said that over the last three days alone, the NHS has announced 477 deaths in London hospitals following a positive test for COVID-19.
Khan hopes the decision will put pressure on the prime minister, Boris Johnson, to take further measures to combat the spread.
Professor Robert West, a participant in the Scientific Pandemic Influenza Group on Behaviours (SPI-B) and also part of Independent Sage, echoed her words, saying the current lockdown rules are "still allowing a lot of activity which is spreading the virus".
"Vaccines give clear hope for the future, but for now we must all stay home, protect the NHS and save lives", he added.
Coronavirus cases are expected to drop in the spring due to vaccination plus the fact people spend more time outdoors, making it harder for the virus to spread.
England's chief medical officer is to urge the public to "act like you've got it" in a major Covid information campaign as the daily reported death toll hit a record high and is not expected to ease for at least a month.
The Office for National Statistics estimated that 1.1 million people in England had coronavirus in the week to January 2, the equivalent of one person in 50.
The emergence of a new, more infectious strain of COVID-19 in the United Kingdom in December has triggered a significant spike in transmission rates across the country, despite existing social distancing measures and tight restrictions on gatherings.
NHS hospitals are treating less than half of the cancer patients they normally would, it has emerged amid increasing fears it is struggling to cope with surging coronavirus cases.
Britain has authorised a coronavirus vaccine developed by Moderna, the third to be licensed for use in the country as it ramps up a vaccination program critical to lifting the United Kingdom out of the pandemic.
