CANBERRA - The New South Wales (NSW) ambulance service is coming under increasing scrutiny after it was revealed two calls for emergency services were required before they attended to critically injured cricketer Phil Hughes.

After being struck on the head while batting on Tuesday, the Australian lay unconscious on the Sydney Cricket Ground field for 15 minutes before paramedics arrived on the scene.

As a result, NSW Ambulance Commissioner Ray Creen will now be called into a meeting with NSW health minister Jillian Skinner regarding their handling of the incident.

Hughes has spent a second consecutive night in an induced coma after being hit on a part of his head unprotected by his helmet. Scans have since revealed a fractured skull and serious bleeding in his brain.

However, despite the severity of the injury, it took 15 minutes and two calls for NSW Ambulance services to arrive. The first call was made six minutes after Hughes was initially struck, at 2:29 p m When an ambulance hadn't arrived eight minutes later, a second call was made.

The response time of 15 minutes far exceeded the NSW Ambulance state average of 7.65 minutes when dealing with "high priority" incidents, in which a patient's life is under threat.

Complicating the matter further was two contradictory statements released by NSW Ambulance following Hughes's injury.

The first read: "The initial triple-zero call was received by NSW Ambulance at 2:37 pm, arriving at the patient at 2:44 pm where two paramedics provided support to the doctor on site treating the patient."

Approximately nine hours later, an amended statement was released, providing differing details to when the first call was received.

"The first ambulance to reach the Sydney Cricket Ground yesterday was dispatched from Prince of Wales Hospital following the triple-zero call.. at 2:37 pm," it read.

"It arrived at 2:44 pm and provided support to the team doctor, who began treating the patient within seconds of the incident."

Subsequently, Creen will meet with Skinner regarding NSW Ambulance's response time, in addition to the conflicting nature of the two statements.

"Due to the conflict information distributed today by NSW Ambulance regarding (Tuesday's) response to the Sydney Cricket Ground, I will be meeting with NSW Ambulance commissioner Ray Creen tomorrow to discuss the circumstances surrounding the incident," Skinner said on Wednesday night.

"My thoughts remain with Phillip Hughes and his family, who I know are receiving the very best care at St Vincent's Hospital."

New South Wales team doctor John Orchard is being credited for his work while waiting for emergency services to arrive. Orchard administered CPR and mouth-to-mouth, before Hughes was taken to St Vincent's where he underwent emergency surgery to relieve pressure on his brain.

Hughes's injury has gained worldwide attention, with sportspeople from around the globe taking to Twitter to send their best wishes to the Australian.

Meanwhile teammates, including Australian captain Michael Clarke, have kept a bedside vigil since he was admitted to hospital on Tuesday afternoon.