Ian Perkin was sacked in December from his £100,000 a year post as finance director at St George's Hospital in Tooting, London after working there for 16 years.
A letter of dismissal criticised his "management style", though he had received a management award six months earlier.
But he had previously supported a junior colleague who had spoken out after being asked to submit inaccurate figures for the number of cancelled operations.
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When NHS staff are punished for telling the truth, just because it rocks the boat a little, then we should all be very worried
"
Ed Davey MP
The junior colleague said although the actual figure was 23, she was told to return a figure of zero.
It then emerged that a figure of zero had been returned for a total of three weeks, during which 86 operations had been cancelled on the day for non-clinical reasons.
System failure
St George's was awarded two star ratings in hospital league tables, rather than three, because of its poor record on cancelled operations.
Mr Perkin told the BBC: "There's always tremendous pressure in the NHS at the moment only to feed good news up the line.
"From memory, we were having to cancel operations at the rate of five or six a week 23 cancelled operations was quite a large number."
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It is accepted that perhaps 'non-applicable' should have been put in the return instead of the zero
"
St George's Hospital spokesman
Mr Perkin's MP, Liberal Democrat Ed Davey, has backed his case.
Mr Davey said: "Ian Perkin voiced concerns about falsified figures on operations and about new financial regimes proposed for the NHS.
"He's been sacked for his pains. When NHS staff are punished for telling the truth, just because it rocks the boat a little, then we should all be very worried."
'Conflicting numbers'
In a statement, St George's Hospital said: "It is true that a zero figure was given but with a strong rider that the Trust had no confidence in the robustness of data collected at that time - there were conflicting numbers being reported in by IT and by hospital bed managers.
"It is accepted that perhaps 'non-applicable'" should have been put in the return instead of the zero.
"The Department of Health accepted this return, and provided further funds for the Trust to improve systems."
It added: "Other issues raised by Mr Perkin are now the subject of an employment tribunal and we would not wish to comment at the moment."
The alleged falsification occurred in September and October 2001, and has since been corrected.