Video report by ITV Wales News reporter Charanpreet Khaira
An ambulance worker has told ITV News the "soul destroying" delays in getting patients into Cwmbran's new Grange University Hospital could end up "costing lives."
The paramedic, who asked to remain anonymous, described more than a dozen ambulances left waiting outside the A&E department with patients during the recent heat wave.
"They're using Covid as a cover," he said.
"The new hospital the Grange was meant to be the fix of everything."
"We're holding 12, 13 14 ambulances outside at a time - 13-14 hours with some patients on the back of an ambulance.
"Our job is to be in the community looking after people. We're not a hospital A&E department cubicle but that's what we're being made to be."
The Grange Hospital has the only emergency department in the Aneurin Bevan University Health Board area.
When it opened last year, the Royal Gwent and Nevill Hall hospitals were downgraded.
The ambulance whistleblower told ITV News that long wait times are having a negative impact on patient care.
"You're there apologising to patients because you can't get them in. The patients become frustrated.
"We're back and forth the A&E department saying 'the patients condition is changing' or 'they need pain relief'."
The Welsh Ambulance Service says it lost more than 2,000 hours in July at Aneurin Bevan University Health Board's emergency departments.
The longest wait for a patient outside the Grange Hospital was just over 13 hours.
The average time a patient waited to be handed over to the emergency department was 1 hour 31 minutes. The target is just 15 minutes.
The health board said the long wait times are down to Covid restrictions in hospital, staff sickness, and unprecedented demand.
And not because there's no longer A&E departments at the Royal Gwent and Nevill Hall.
Dr James Calvert, Medical Director at Aneurin Bevan University Health Board said: "They've not been downgraded - they've been repurposed.
"We opened a new hospital system that was perfectly designed to meet the needs of the people of Gwent."
The ambulance whistleblower said he felt he needed to keep him identity secret because of a "bullying culture" within the Welsh Ambulance Service.
A Welsh Ambulance Service spokesperson said: “We pride ourselves on being a kind, caring and compassionate organisation, so we take this very seriously, and are understandably saddened that our colleague feels this way and are actively working to ensure a psychologically safe environment.
“To this end we have been conducting a Trust wide listening exercise to refresh our organisational behaviours and will be receiving the output of this over the next few weeks, which will shape our future actions.”