Professor Kevin Fenton also pointed to figures suggesting the capital’s coronavirus cases are no longer falling at a rapid rate. His stark warning comes just two days after Londoners began easing back into normal life with the reopening of clothes shops, restaurants, bars and theatres.
The city of nine million people is currently in the Government’s “high alert” Tier 2 lockdown category, which means people are not allowed to mix indoors with anyone not in their household or support bubble.
Groups of up to six are permitted to socially gather outside – in a public space or private garden.
People living in areas under Tier 3 are not allowed to meet socially with anyone not in their household or support bubble.
Restaurants and bars in Tier 2 are permitted to open while hospitality venues in Tier 3 are only allowed to offer takeaway, deliver or click and collect services.
Prof Fenton Londoners could face being banned from pubs and restaurants ahead of the Christmas holiday.
He urged people living in the capital to diligently “stick to the rules” and observe social distancing when out and about.
Figures released by the Department of Health show a sharp drop in daily coronavirus cases during mid-November – half-way through Boris Johnson’s second national lockdown.
But by November 23 cases in London had begun to level off.
READ MORE: R-rate in my area: UK map shows regions where Covid cases increasing
On Friday the Government said a further 504 people had died within 28 days of testing positive for COVID-19 as of Friday.
The rise brought the UK’s total to 60,617.
Separate figures published by the UK’s statistics agencies for deaths where COVID-19 has been mentioned on the death certificate, together with additional data on deaths that have occurred in recent days, show there have now been 76,000 deaths involving the virus in the UK.
And a further 16,298 coronavirus cases were recorded on Friday, taking the country’s overall tally to 1,690,432.
The UK’s mounting death toll – the highest in Europe – has piled pressure on the Prime Minister to make crucial decisions.
This week he hailed the approval of a COVID vaccine from Pfizer and BioNTech as “fantastic news”.
But Downing Street was forced to defend the UK medicines regulator which approved the jab after America’s top infectious disease expert expressed scepticism over the timeline.
Dr Anthony Fauci said Britain’s approval of the vaccine was “rushed”.
In comments he has since rowed back from, Dr Fauci, the director of the US National Institute of Allergy and Infectious Diseases, said Britain “kind of ran around the corner of the marathon and joined it in the last mile” after becoming the first country in the world to sign off on allowing the vaccine to be administered.
The Prime Minister’s deputy spokesman told reporters: “You will have seen that he (Dr Fauci) has now withdrawn those comments and apologised.
“I would just point to the fact the MHRA is a world leader in its field and has followed rigorous international standards in terms of its assessment of the vaccine to ensure it meets the standards of safety and effectiveness and quality.
“The CEO of the MHRA has been quite clear that no corners have been cut at all.”