It comes as 16 ambulances from South Central Ambulance Service (Scas) were left waiting to transfer patients to the emergency department on Monday night.
Some of the patients were waiting for more than two hours.
But Portsmouth Hospitals NHS Trust, which runs the Cosham hospital, said there is an extremely high demand on its emergency department with Portsmouth Clinical Commissioning Group confirming the hospital is currently on ‘black alert’.
Mark Ainsworth, director of operations at Scas, said: ‘On February 22, Scas experienced significant handover delays at Queen Alexandra Hospital which unfortunately reduced the availability of ambulances and crews to attend incoming emergency calls.
‘We are becoming increasingly concerned about this and the impact it has on our ability to respond to patients.
‘At its peak time we had 16 crews waiting to hand over their patients, some of which were held back for more than two hours.’
He added: ‘The greater impact is for those patients who are waiting for an ambulance responses following a 999 call. We experienced some long delays to these patients.’
A spokeswoman for Portsmouth Hospitals NHS Trust said: ‘There is currently an extremely high demand on our emergency department, with huge numbers of very sick, frail and elderly patients needing urgent care.
‘To put this into context, we are currently receiving more than 15 per cent additional attendances in the emergency department compared to this time last year.
‘The acuity of patients and increased elderly admissions does impact on our ability to accommodate, in a timely fashion, all ambulance arrivals to ED.’
She added that due to the demographic of their patients, Portsmouth received more ambulances than any other trust served by Scas.
Portsmouth North MP Penny Mordaunt said patients needed to be admitted, as well as discharged, from QA quicker.
Ms Mordaunt said: ‘Having been out with our ambulance crews in the past they work hard to only take those who need to be in hospital to the QA.
‘The key issue is to speed up patients going through A&E.
‘As well as the QA’s own plans, we have written to [Portsmouth Hospitals NHS Trust chief executive] Ursula Ward to suggest some other options they might consider.
‘This includes working with a local care provider to reduce the time and admin to secure care packages for those being discharged.
‘We are also seeking a meeting with Jeremy Hunt regarding this new idea.’
In December 2014 The News revealed that ambulances waited for an average six hours outside QA before they could hand over their patients.
Between April and November that year, the goal of a 15-minute handover at the A&E department was exceeded 6,055 times.