While one trust’s intensive care unit (ICU) was completely full for six days, and another was at maximum capacity for four days.
It comes as NHS hospitals are already showing signs of significant pressure, even before the expected surge in Omicron patients expected this Christmas.
Sadiq Khan declared a “major incident” over the huge rise in Omicron cases in the capital, saying Covid-19 patients in hospitals had gone up by 29%.
London local authorities make up 18 of the 20 council areas in the UK with the highest Covid-19 rates.
NHS England figures revealed Whittington Health NHS trust - a small acute site - was the busiest hospital group in the capital for ICU patients, at 99% capacity up to December 12.
The trust is currently meeting demand for its smaller number of ICU wards and is able to open additional beds as required, LondonWorld understands.
The trust was closely followed by Barts Health and Homerton University Hospital NHS trusts, which were both at 96% capacity.
Barking, Havering and Redbridge University Hospitals, Guy’s and St Thomas’, Imperial College Healthcare and King’s College Hospital NHS trusts were also all over 90% full.
While Chelsea and Westminster Hospital, Kingston Hospital, Lewisham and Greenwich, London North West University Healthcare, North Middlesex University Hospital, Royal Free London, St George’s University Hospitals and the Hillingdon Hospitals NHS trusts were all at over 80% capacity in the same week.
However, Epsom and St Helier University Hospitals and University College London Hospitals NHS trusts were over 70% full, and Croydon Health Services NHS trust was 66% full.
A spokesperson for Homerton University Hospital NHS trust said: “Our critical care beds have been busy because we have been working hard to relieve the elective surgery waiting lists.
“Covid-wise we have seen an increase in the number of patients admitted in the past couple of weeks and have two wards set aside for their care.”
While a spokesperson for Whittington Health NHS trust said: “While the winter period always results in additional pressure on the NHS, we work with partners across the system to ensure that there is capacity to provide care and treatment to those who need it.
“We have a flexible approach to the number of beds where we can care for our sickest patients and this is reviewed regularly in order to meet demand.
“While we provide intensive care to patients with Covid-19 and those with different healthcare needs, everyone can help to manage pressure on the NHS by getting vaccinated, wearing masks in public places and social distancing.”
The NHS England figures also revealed 23% of ambulances had to queue outside A&Es for half an hour or more before patients could be admitted in the week to December 12, while five hospital trusts in England had no available critical care beds on any day that week.
Ambulances were diverted away from full A&Es in England a total of 28 times, and there was an average of around 60,000 NHS staff absent from work each day, a fifth due to Covid-19.
Professor Stephen Powis, NHS national medical director, said: “Staff are continuing to go above and beyond looking after thousands of seriously ill Covid patients, delivering hundreds of thousands of jabs into arms every day while continuing to deal with higher levels of pressures for this time of the year.
“No one wants to spend more time in hospital than needed, and local NHS services are continuing to work closely with social care providers so patients can be discharged when they’re fit to leave.
“So as the NHS once again ramps up to deal with what is going to be an incredibly challenging winter, the best thing you can do to help is to come forward and get your jab.”