The boss of Birmingham's largest NHS trust has resigned just weeks after its plans for a #559 million super-hospital were approved by the Treasury.

Mark Britnell, chief executive of University Hospital Birmingham NHS Foundation Trust (UHB), will leave at the end of this month after contracts for the new hospital have been signed.

The 40-year-old, who led the trust to become one of the highest performing in the UK and saw it achieve foundation status, has been appointed chief executive of the newly-formed South Central Strategic Health Authority - which covers an area from Oxford to the Isle of Wight. He will formally take up the post in July.

He joined UHB as director of operations in February 1998 and was appointed chief executive in November 2000.

Mr Britnell said: "It is with mixed emotions that I leave the Trust. I am delighted to be taking on such an important role for the NHS but I will miss the staff at UHB. We have some of the finest staff in the NHS and I know they will go from strength to strength as the new hospitals rises from the ground."

Bosses at Birmingham and the Black Country Strategic Health Authority will formally announce Mr Britnell's resignation on Monday, but trust staff were told about his departure on Tuesday.

John Charlton, UHB chairman, said: "I am pleased and proud for Mark. Many people deserve credit for our new hospital success but Mark has figured prominently in the eight years we have worked on the scheme together.

"We have an outstanding team who will continue with our excellent progress and look forward to appointing a first class successor in due course."

Until his successor is appointed, trust chief operating officer Julie Moore will be acting chief executive.

Mr Britnell began his career on a fast-track NHS management training scheme after he graduated from the University of Warwick. He worked for the Australian College of Health Service Executives in Melbourne and Sydney before being seconded to the NHSE.

After working as a general manager at St Mary's Hospital in London, Mr Britnell was appointed director at Central Middlesex Hospital in 1995. The following year he became project director for the hospital's Ambulatory Care and Diagnostic PFI scheme, the first of its kind in the UK.

He led the merger of Central Middlesex and Northwick Park Hospital in 1997 before he moved to UHB in 1998.