Health select committee chair Stephen Dorrell has written to the health secretary raising concern about the application of a confidentiality agreement signed by Gary Walker, the former United Lincolnshire Hospitals Trust chief executive.

Mr Walker yesterday said he had breached a confidentiality agreement signed in October 2011, ahead of an employment tribunal which had been due to take place, to raise concerns over patient safety.

Before the interview was aired Mr Walker was sent a letter from law firm DAC Beechcroft acting on behalf of United Lincolnshire Hospitals.

The lawyers’ letter said:  “Should you breach the term relating to confidentiality, you will immediately repay to the trust on demand all sums paid under this agreement in full and you agree that we may recover the compensation sum from you as a debt, together with our reasonable costs, including reasonable fees in doing so. You hereby indemnify the trust for any losses suffered as a result thereof.”

The message also said the gagging order covered Mr Walker’s family, and told him to withdraw any statements he made in media interviews.

Mr Dorrell wrote to health secretary Jeremy Hunt yesterday, highlighting the findings of the Francis public inquiry into Mid Staffordshire Foundation Trust on the subject of confidentiality agreements.

Mr Dorrell said that, while the committee was normally reluctant to wade into individual employment disputes, “this argument is, however, different”.

He wrote: “I am sure you will understand therefore, particularly in the light of the government’s endorsement of the care recommendations of the Francis report about the important need for a fundamental change of culture within the NHS, that we were concerned and disappointed to hear that Mr Walker had received a lawyers’ letter which he has interpreted as reinforcing the constraints upon him under the terms of the ‘gagging clause’ in his compromise agreement.

“The committee intends to write to Mr Walker to invite him to set out in detail the nature of the concerns which lay behind the breakdown of his relationship with the Lincolnshire Trust.

“Before doing so, however, I would be grateful if you would confirm that neither the trust nor any other NHS body will seek to enforce any clause in Mr Walker’s compromise agreement which would impinge on his capacity to respond fully to the committee’s request.”

Mr Dorrell also pointed out that the committee had been assured by the Department of Health in December 2011 that gagging orders were “not acceptable”, and “inconsistent with the Public Interest Disclosure Act.”

The gagging order prevented Mr Walker him from speaking about his dismissal, or from acknowledging the existence of the deal.

Mr Walker was been fired in 2010 for gross misconduct for allegedly swearing in board meetings.

Yesterday Mr Walker said his trust board decided to abandon waiting time targets because of soaring emergency demand in 2008 and 2009.