Mr Khan and London Councils chair Cllr Georgia Gould claimed closing places of worship should be on the table as well as make mask-wearing mandatory outside the home. Meanwhile, an insider claimed, depending on data, new restrictions could be decided on by the weekend, meaning a tougher lockdown could be just days away.
They said without any new measures, there could be an “unsustainable strain” on the NHS and public services.
Speaking today, Mr Khan said more than 10,000 Londoners have now died with COVID-19 and action needed to be taken immediately.
The letter also urges four other more temporary measures which include an urgent review of what constitutes essential and non-essential retail and stricter guidance on how retailers can prevent unsafe queues and crowding.
They also demand prohibiting click and collect services at non-essential retail chains and stronger guidance on size restrictions for weddings, funerals and similar gatherings.
The letter adds: “We recognise how difficult these decisions are and how they will impose further tough restrictions on Londoners.
“With new levels of infection remaining high we are left with little choice but to ask that you implement them.”
In a statement today, Mr Khan added: “This epidemic is far worse than it was in spring, the pressures on the NHS are far higher, yet the lockdown measures are much lighter.”
Adding of the restrictions, he said: “We think that’s the best way to save lives and stop the NHS being overwhelmed.”
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“We know how tough this is for Londoners.
“Today, the thoughts of London leaders are with the thousands of Londoners in hospital battling Covid and the amazing carers fighting to save lives.
“We owe it to them to do all we can to keep ourselves and our loved ones safe.
“This is a dark and difficult time for our city but there is light at end of the tunnel with the vaccine rollout.
“We are asking Londoners to come together one last time to stop the spread – lives really do depend on it.”
Health Secretary Matt Hancock said coronavirus lockdown restrictions will remain in place in England for as “long as they are necessary”.
A UK Government source told Express.co.uk: “We can’t rule anything out and our measures are always kept under constant review.”