NHS boss Sir David Nicholson is under fresh pressure after admitting giving incorrect evidence to MPs.
In a letter to the Public Accounts Committee, Sir David said he had given wrong information while describing how he dealt with a 'whistleblower' in 2009.
He insisted on Monday that Gary Walker, former head of United Lincolnshire NHS Trust, had not explicitly identified himself as a whistleblower, or raised concerns about patient safety.
But appearing before the Health Select Committee on Tuesday morning, Mr Walker flatly contradicted Sir David's account. He handed over a letter he had sent to the NHS chief executive four years ago complaining of bullying by managers at East Midlands Strategic Health Authority (SHA).
He wrote: "I assume the Department of Health has a policy on whistle-blowing and would therefore like this letter to be considered in that context and not freely copied to the SHA or the local PCT (primary care trust)."
Mr Walker was sacked from his job in 2010, allegedly for swearing in a meeting. He maintains the real reason was his refusal to prioritise waiting list targets over emergency care for patients, and says he was subject to a "gagging clause" as part of the terms of his pay-off.
Mr Walker told the MPs: "I wrote to David Nicholson telling him everything that went on...
"I disclosed to him the threat to patients' health and safety due to the fact that I was being forced to comply with targets, the threat to health and safety of patients due to SHA bullying members of the ULH staff, asking me to leave my post which is also bullying and intimidation and the various reviews that the health authority had carried out were biased and flawed.
"I asked for protection as a whistleblower in that letter in the last paragraph and as I said, yesterday at the public accounts committee David Nicholson denied all of that."
The Spectator reported that Tory MP Charlotte Leslie had written to David Cameron renewing her call for Sir David to go.
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