An internal investigation is under way at South Central Ambulance Service regarding the way it operates its call centre in Bicester.

The investigation has been prompted by research by The Telegraph involving an undercover reporter.

The Telegraph said it spent seven weeks working undercover at the SCAS call centre and claimed patients who called the NHS 111 service were being denied ambulances even if they were experiencing symptoms of a heart attack.

The 111 service was set up as a non-emergency alternative to 999 to relieve the pressure on the health service, including A&E departments.

According to the investigation, call handlers were told that when ambulances were “stacked” due to a backlog of requests, ambulance crews should not be sent out without the approval of a clinician unless the patient was having a stroke or a heart attack.

South Central Ambulance Service spokeswoman Catherine Morrow said it took the issues and points raised by the undercover reporter “very seriously”.

She added: “In response to the comments raised, we will follow the principles of our ‘Whistleblowing Policy’ to investigate the alleged issues identified.

“We have appointed an investigating office to oversee this process.

“We have informed relevant stakeholders of the issues raised, including our regulators and commissioners, as a reflection of the importance we attach to the concerns raised.”

She added SCAS took any issues relating to staff conduct very seriously, particularly in relation to patient safety and experience.

Ms Morrow said: “Where we receive reports of inappropriate conduct or behaviour we strictly enforce our internal policies and procedures.”