Britain will face an exponentially growing death rate from Covid-19 within weeks unless Prime Minister Boris Johnson’s government moves urgently to halt a rapidly spreading second wave of the outbreak, the country’s senior medics said on Monday.

The United Kingdom 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 United Kingdom.

“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% of the population have antibodies to the virus, though in London around 17% of the population may have antibodies, Vallance said.

Speed and action are urgently needed, Vallance and Whitty said, adding that as winter was approaching the COVID problem would haunt Britain for another six months at least.

Johnson is due to speak on Tuesday.

Health Secretary Matt Hancock said the restrictions would be different to last time. The government wants to crack down on socialising but schools and many workplaces will stay open.

“If we do have to take action, it will be different to last time and we’ve learnt a huge amount about how to tackle the virus,” he told ITV.

“Schools aren’t where a lot of the transmission happens, it’s more about people socialising,” he said.

Asked about Christmas and if people would be able to hug their relatives, he said he wanted it to be as normal as possible.

“If this runs out of control now, we’ll have to take heavier measures in the future,” Hancock said.

The official UK death toll stands at 41,777 people.