LONDON (Reuters) - 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. Commuters walk across the London Bridge during the morning rush hour, amid an outbreak of the coronavirus disease (COVID-19), in London, Britain September 21, 2020. REUTERS/Hannah McKay 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. Advertisement “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. Related Coverage London Mayor proposes new COVID-19 restrictions England"s pubs to close early to tackle COVID-19 rise - The Sun 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. Health Secretary Matt Hancock said new restrictions would be different to last time. The government wants to crack down on socialising but schools and many workplaces will stay open. “GREAT CONCERN” Advertisement The chief medical officers for England, Scotland, Wales and Northern Ireland recommended all four nations move up to COVID-19 alert “Level 4” - an epidemic is in general circulation; transmission is high or rising exponentially. Prime Minister Boris Johnson told the leaders of the three devolved nations that rising COVID-19 cases were a cause for “great concern” and he was committed to working with their administrations to tackle the virus. The Sun newspaper reported that Johnson would announce a 10 pm closing time for pubs, bars and restaurants. He is due to address parliament on the coronavirus issue on Tuesday. Slideshow ( 3 images ) Northern Ireland said it would extend existing restrictions in some localities on households mixing indoors across the whole of the province from Tuesday, while Wales slapped curbs on four more areas, also from Tuesday, leaving just under a third of the Welsh population under restriction. The Welsh measures prevent people entering the areas without a reasonable excuse such as education or work. People will also only be able to meet people they don’t live with outdoors. Scottish First Minister Nicola Sturgeon said that additional restrictions were almost certain to be imposed. The official UK death toll stands at 41,788 people. Reporting by Guy Faulconbridge, Kate Holton, Estelle Shirbon; Editing by Angus MacSwan, Toby Chopra and Gareth Jones