A culture of fear means that whistleblowers are still reluctant to speak out in Northern Ireland, a watchdog has warned.
Kieran Donnelly cited the Renewable Heat Incentive (RHI) scandal as he referred to "real and perceived barriers" that exist.
He said public sector leaders must tackle head-on the issues stopping concerns from the public and workers being listened to and acted on.
Mr Donnelly, the Comptroller and Auditor General, was speaking as new guidelines were published on Thursday. The Raising Concerns report references the RHI Inquiry findings published in March, which made recommendations on how public sector organisations should deal with concerns raised by the wider public.
The inquiry found that a whistleblower who spoke out about the botched green energy scheme should have been treated better.
Janette O'Hagan repeatedly contacted officials between 2013 and 2015 to highlight abuse, but her warnings were overlooked.
The inquiry concluded that her treatment "fell well below the standard she was entitled to expect".
Thursday's report also refers to a 2015 publication by Sir Robert Francis QC, who led the public inquiry into the Stafford Hospital scandal which made significant recommendations for the health service in England. The value of whistleblowers was highlighted in a recent Audit Office report on Land & Property Services' LandWeb project. It detailed how a tip-off led auditors to uncover failings around poor planning and value for money.
However, Mr Donnelly said a culture change is needed to encourage more to speak out.
He said: "I continue to receive correspondence from public sector employees who have tried to do the right thing by raising concerns with their employer, but have been ignored or not received a fair hearing, or who have even suffered as a result of speaking up. This situation must change. The recent RHI Inquiry highlighted the consequences of genuine concerns not being properly addressed.
"Senior leaders in every public body in Northern Ireland need to take action to address the real and perceived barriers to raising concerns.
"They should formally review the effectiveness of their arrangements for responding to concerns against the good practice principles set out in this guide.
"It is important that such reviews are more than tick-box exercises.
"Strong and visible leadership is key to promoting the necessary culture change."
Sue Gray, Permanent Secretary of the Department of Finance, said: "Recognition that raising concerns should be a normal, everyday event is welcomed, and is an approach that my department has encouraged in our work in this area recently.
"I was also delighted to see that the importance of an open, supportive culture is emphasised in the guide and I believe there is more work we can do on this."
The new guidelines encourage organisations to put in place effective arrangements to hear, consider and act on concerns raised by whistleblowers.
These include an obvious and well-signposted route for people wishing to raise a concern in the public interest.