Medical chief's safety warning: Boss of NHS in London says wards in some parts of the country are unsafe because of desperate shortage of doctors and nurses Warning: Andy Mitchell, head of the NHS in London, said that sometimes patients were at risk because of thin resources Hospital wards and departments in some areas of the country are unsafe due to a desperate shortage of doctors and nurses, a senior health boss has admitted. Dr Andy Mitchell, who is overseeing the health service in London said there were times of the day when patients are at risk because staff are spread too thinly. He warned that hospitals in the capital were 'at breaking point' and admitted senior managers are constantly 'trying to patch up'. It is very rare for such a senior figure in the health service to paint such a grim picture about the current pressures facing hospitals. But Dr Mitchell's warning comes ahead of a report today which is expected to admit many hospital departments in London are no longer 'fit for purpose' and may have to close. It will state that half of the capital's A&E units should shut along with some maternity departments and specialist children's centres just to ensure they are safe and affordable. Dr Mitchell, the medical director for NHS England in London said: 'At times, throughout the week, even throughout the day, services aren't safe. I feel anxious sometimes about saying it is unsafe, because I, of course, have got a responsibility to change it and improve it, but we are trying to patch up all the time. What we cannot do is carry on with the idea that all hospitals provide a whole range of services. That is completely unsustainable and would become, frankly, unsafe, and is becoming unsafe in many areas. 'The public doesn't fully understand, isn't really sufficiently aware, that many places don't meet acceptable standards of care.' Closure: Today's report is expected to recommend the closure of 50 per cent of all casualty departments Only last week a report by the health watchdog Monitor warned that the NHS would be £30 billion in the red every year unless it made crucial changes to the way hospitals and other services run. Many experts believe smaller hospitals will have to close because there are just not enough doctors, nurses or resources to ensure they can carry on running safely. But the issue is highly controversial as many of the public are very attached to their local hospital and do not want to travel miles for an appointment or to visit loved ones. Chaos: Shadow Health Secretary Andy Burnham blamed the problems on David Cameron Already there has been fierce opposition from the public where departments are under threat including in Lewisham, South London, where 15,000 took to the streets in January in protest against the closure of the A&E unit. Today's report by NHS England, the new body in charge of running the health service, is expected to say: 'London's hospitals are becoming increasingly unsustainable, both clinically and financially. In many cases they are no longer fit for purpose. It will state that to make the health service safer and affordable, the number of casualty departments will have to reduce by 50 per cent. The report will also call for some maternity units and children's services to close so care can be provided by larger, more specialised centres. Although it only concerns the health service in the capital, it will be seen as a blueprint for the rest of the country which is facing the same pressures. Shadow health secretary Andy Burnham blamed the NHS's costly health reforms for the lack of funds. He said: 'The severity of this funding crisis is entirely of David Cameron's making. People pleaded with him to stop the reorganisation so the NHS could focus on the financial challenge. He refused to listen and threw the entire system into chaos.