A senior councillor says the head of a hospital trust should resign if mismanagement is blamed for it being millions of pounds more in debt than first thought.

Bob Smytherman, the leader of the Liberal Democrat group at Worthing Borough Council, spoke out after it emerged Worthing and Southlands Hospitals NHS Trust ended the last financial year £10.6 million in the red instead of the reported £6 million.

Surrey and Sussex Strategic Health Authority (SHA) has launched an investigation and has sent a team into the trust to carry out an independent review.

An SHA spokesman said the aim was to find out why the extent of the £4.6 million overspend was not spotted and why proper controls to monitor spending were not in place.

He said: "We want to have their recommendations in the next few weeks. The broader findings of the report will be made available to the public."

The news comes in the same week it emerged the trust's director of finance Lovat Timbrell and strategy and development director Martin Pearson had resigned from their £70,000 a year posts.

Mr Timbrell has been at the trust for eight years and has been temporarily replaced by Peter Hollinshead.

Mr Pearson worked at the trust for 17 years. The trust said the two resignations were not linked.

A hospital spokeswoman said: "Of course we take this whole issue very seriously but it would be wrong at this stage to pre-empt the outcome of the review which has now started."

Trust chief executive Stephen Cass said: "We welcome this review, which will enable us to establish how the figures were gathered and reported and also help us to make sure we retain an accurate financial reporting system from now onwards."

Coun Smytherman said: "We need to have an open and honest debate about where things have gone wrong so we know exactly what has happened here.

"If it transpires that mistakes were made and the trust is at fault then someone has to be held accountable for it.

"As the head of the trust that has to be the chief executive. If that is the case then I would want to see him resign. If it emerges that it is the fault of funding and it is the Government which has made a mistake then I would want to see the Health Secretary resigning. We need to see the full facts of the whole case but someone has to be accountable."

Worthing Council leader Keith Mercer said: "This refers to financial activity in the last year and is not expected to have an adverse effect on the quality of care for patients.

"The issue is now being properly investigated. The hospital is doing the right things in this case. I will expect managers to address the findings of the enquiry in a professional manner."

The trust has an annual budget of around £130 million.

Beda Oliver, from the independent watchdog the Worthing and Southlands Patient and Public Involvement Forum, said: "Obviously an increased debt like this is always of concern to us because the trust is going to have to make the necessary savings. We will be monitoring the situation closely and will be waiting to see the results of the SHA report when it comes out."