Ambulance bosses could be forced to step down after failings over the handling of NHS 111 calls.
Health regulator Monitor has criticised South East Coast Ambulance Service for a project which increased how long some patients were waiting for ambulances.
They transferred some NHS 111 calls to the 999 emergency system to give staff up to 10 minutes more time to respond to the call.
The project, which ran between December 2014 and February 2015, was launched in response to the high pressures it was facing last winter.
Extra time was given to calls which were placed in the second most serious category - these are for issues that may be life threatening but are less time critical.
Due to national standards 75% of these calls have to be dealt with within eight minutes, but under the project the trust gave itself up to 10 extra minutes to re-assess what type of advice or treatment the patients needed and whether an ambulance was required.
Monitor said there was a clear failure of management processes and it appears the trust’s board was not fully aware of the changes.
They said they had concerns about how the trust is being run and how decisions are taken.
The health regulator also said it has reasonable grounds to suspect the trust is in breach of its license to provide NHS services.
They are working with SECAmb to identify what needs to be done to review the impact this project could have had on patients.
The trust will also commission a review into the way the project was handled, and more widely into the way it makes decisions.
Monitor has added a condition to the trust’s license so if sufficient progress isn’t made, further action could be taken - including changing the leadership team at the trust.
Paul Streat, Monitor’s regional director, said: “Over the winter, there were significant demands on the NHS and it is understandable that trusts want to explore better ways of delivering the best possible care.
“But this project was poorly managed from the start, done without the proper authorisation and without enough thought given to how it might affect patients.
“We have asked the trust to review the action it took to make sure there was no harm to patients, and look again at the way decisions are taken to prevent something like this happening again.”
Paul Sutton, chief executive, said: “The process was undertaken to ensure that the right response was provided to patients and that we were able to respond promptly to the most seriously ill patients.
“However we recognise that it was not well implemented and we did not use our own corporate governance processes correctly. These are serious findings.
“We have already begun to take steps to address Monitor’s concerns and as part of this process, independent reviews will assess how decisions are made within the Trust, governance processes and our approach to patient safety.
“As a Trust, we remain extremely proud of the high quality and compassionate clinical services that SECAmb provides to our patients.”