Britain will face an exponentially growing death rate from Covid-19 within weeks unless urgent action is taken to halt a rapidly spreading second wave of the outbreak, the country’s senior medics said on Monday.

The UK already has the biggest official Covid-19 death toll in Europe — and the fifth largest in the world — while it is borrowing record amounts in an attempt to pump emergency money through the damaged economy.

But new Covid-19 cases are rising by at least 6,000 per day in Britain, according to week-old data, hospital admissions are doubling every eight days, and the testing system is buckling.

Chris Whitty, the government’s chief medical officer, and Patrick Vallance, its chief scientific adviser, cautioned that if left unrestricted the epidemic would reach 50,000 new cases per day by mid-October in the UK.

“If this continued along the path... the number of deaths directly from Covid... will continue to rise, potentially on an exponential curve, that means doubling and doubling and doubling again and you can quickly move from really quite small numbers to really very large numbers,” Whitty said.

“If we don’t do enough the virus will take off and at the moment that is the path that we are clearly on and if we do not change course then we're going to find ourselves in a very difficult problem.”

The virus is spreading across all areas of the country and less than 8 per cent of the population have antibodies to the virus, though in London around 17 per cent of the population may have antibodies, Vallance said.

Prime Minister Boris Johnson is due to speak on Tuesday.