There were over 12,000 new cases of Covid-19 coronavirus in four South-East London boroughs in the seven days up to January 3, new data mapped by Public Health England (PHE) shows.

On Saturday (January 9), PHE's colour-coded interactive map showed the South-East London boroughs of Lewisham, Bromley, Greenwich and Bexley all coloured a dark purple, signalling high prevalence of the virus and its rapid spread in the region.

In total, the number of new cases in those four boroughs in exceeded 12,000, with all four confirming more than 3,000 new cases in the week up to January 3.

That chimed with health officials increasing alarm at the spread of Covid-19 in London, deemed to be "out of control" by Mayor Sadiq Khan who has declared a major incident in relation to the virus.

In Lewisham, for example, 3,162 new cases of Covid-19 were confirmed over the period, a rise of 686 relative to the previous week, up 27.7 per cent.

That gave the borough a 'rolling rate' of new cases per 100,000 people of 1,033.9, far higher than the average for England as a whole of 626.2.

News Shopper: Screenshot from PHE dashboard Screenshot from PHE dashboard

London is one of the most severely-hit epicentres of the virus in the UK at present, with Mayor Sadiq Khan warning that "our NHS could be overwhelmed" without coordinated action to slow the spread.

Other South-East London boroughs showed similarly alarming data to the Covid-19 figures emerging from Lewisham.

In Bromley, there were 3,659 new cases of coronavirus in the week ending January 3, up 508 or 16.1 per cent on the previous week, for a rolling rate even higher than Lewisham's, at 1,101.0.

News Shopper: Screenshot from PHE dashboard Screenshot from PHE dashboard

Greenwich meanwhile reported 3,173 new cases, up 799 or 33.7 per cent. It's rolling rate was 1,102.0 per 100,000 people.

News Shopper: Screenshot from PHE dashboard Screenshot from PHE dashboard

And in Bexley, there were 3,032 new Covid-19 infections confirmed over the period, up 240 or 8.6 per cent, for a rolling rate of 1,221.2.

News Shopper: Screenshot from PHE dashboard Screenshot from PHE dashboard

PHE London said the NHS was now under "immense pressure" in the city with 800 patients being admitted to hospital every day currently.

"In order to ease the burden on our hospitals, we must first stop the spread. That means we have to stay at home. Cut your contacts, reduce your movements, do as little as possible," Professor Kevin Fenton, London PHE's regional director, said.

More the latest Covid-19 data from where you live, click here.