A health authority has been told it will be stripped of its powers and top NHS managers sent in if it do not act to turnaround its £10m deficit.

West Norfolk Clinical Commissioning Group (CCG) boss Dr Paul Williams wrote to GPs last week describing the 'dire' financial position of the organisation, which finished the last year £7.8m in the red and looks set to finish this year with an extra £10m overspend.

CCGs, which control the majority of the NHS budget and commission services for their area, are legally bound to break even - and are encouraged to post a surplus.

But Dr Williams said every year in West Norfolk health chiefs find themselves 'behind the curve in autumn, but with some hard work and clever accounting we managed to be where we were meant to be in April'.

However, a combination of 'unreasonable assumptions made over several months' and no provision being made for previous one-off cash budgets resulted in an overspend.

And Dr Williams said: 'This year, because budgets were set without taking account of that deficit, and no allowance was made to pay back that deficit, the situation is catastrophically worse.'

Dr Williams' letter said the CCG faced a deficit of £10m this year plus £7.8m last year 'on top of that' - a total of £17.8m. But a spokesman said this was incorrect and £10m was the total figure.

Dr Williams and other top ranking CCG executives were summoned to 'face a star chamber of NHS executives' last week. Dr Williams said: 'The regional director Dr Paul Watson was the lead inquisitor alongside three other NHSE (NHS England) big wigs. At the end of the meeting we were left in no doubt that unless we immediately started reducing expenditure then NHSE would not hesitate to disempower the governing body and current executives and send in manager under legal direction to turn things around.'

He added: 'They would have little regard for the long term consequences of their actions, their prime imperative would be to simply save money.'

Dr Williams warned of 'very unpleasant consequences' and 'short term pain' as the organisation has three weeks to come up with a plan.

A CCG spokesman today said the organisation was 'immensely disappointed to find itself heading towards a significant overspend'.

He stressed the money had all been spent on patient care and management were working hard to fix the situation.

The CCG will be looking for cost saving across the health system. However three areas were highlighted by NHSE - locally commissioned services, demand management, and sending mental health patients out of the area.

Locally commissioned services (LCS), also known as local enhanced services, are provided over and above their core NHS contract. They cost around £2m a year in West Norfolk and include taking blood samples, peer review of referrals, treating minor injuries and paying for treatment rooms.

In his letter Dr Williams said it was highly likely the budget for these services would be reduced or cease completely for this financial year.

But a CCG spokesman said the letter was the 'worst case scenario' and payments to practices have not been reduced nor were they proposing any cuts to LCS this financial year.

He said: 'The CCG will review all locally commissioned services for 2018/19. We shall want to look at their effectiveness, to make sure that every pound we spend delivers maximum quality and value for money. If any LCS are changed, core GP services will not be affected.'

Demand management is aiming to halt or reverse the number of people going into hospital when they could be cared for at home.

The spokesman added: 'It is vital to stress this is not just about GP practices. Every part of the NHS must make financial savings and efficiencies, and the CCG has a duty to remain within its budget.

'West Norfolk takes a responsible approach to this. We have put in place transformations that make savings and also improve patient care, such as a virtual ward and care home matrons to keep people safe and well in their homes, and reducing the use of expensive medicines when there are equally effective and less expensive versions.

'We shall continue this efficiency drive across all areas of the NHS to deliver maximum efficiency and maximum quality of care and reduce the deficit we face.'