Jeremy Hunt has warned senior NHS executives there will be consequences if they have wrongly gagged a former manager from speaking out about concerns over patient safety.
The health secretary said he was concerned that Gary Walker, the former chief executive of United Lincolnshire Hospitals Trust, appeared to have been "leaned on".
Walker broke his silence on Thursday to allege that he was forced out of his job in 2010 because he put patient safety ahead of Whitehall targets. He has received a lawyer's letter threatening legal action for breaching the terms of the package agreed in settlement of his unfair dismissal claim. That package was reported to be worth £500,000.
Hunt said he was ready to order NHS bosses to reverse the gagging order if it was found to have breached NHS guidelines. He has written to Paul Richardson, chairman of the trust, to tell him it was not an acceptable way to behave when an NHS manager raised concerns about patient safety.
"I don't think this is acceptable, I think it is the wrong thing to do," Mr Hunt told BBC Radio 4's World at One programme.
"I don't want to make a judgment about the truth or otherwise about what Gary Walker said. Obviously there are very, very serious allegations that we need to get to the bottom of, but I'm determined to get to the bottom of it."
The Francis report into the Mid-Staffordshire scandal called for a ban on the use of gagging orders that prevented concerns being raised about patient safety.
Hunt said he had written to the trust to find out the contents of Walker's settlement so he could establish if it was in line with NHS guidelines on whistleblowing. "If it isn't, of course I will insist that they change it," he said.
"First of all, we must have a culture where people are not afraid to speak out and secondly I was very concerned that it appeared that someone was being leaned on not to speak out, and most of all I want to get to the bottom of whether there is any truth in what he was saying."
Asked if senior staff at the trust faced being sacked if there had been mismanagement, he said: "If they have got this wrong there will be consequences, yes, but I want to investigate and find out and get to the bottom of what actually happened before I make a judgment on that."
Hunt said that for too long there had been a culture of celebrating success in the NHS but "not being honest about failure".
