The Welsh Ambulance Service is in crisis and lives are being lost because of failures, claims its former head.
Mr Thayne says lives are being lost because of failures
Roger Thayne resigned as interim chief executive saying he was asked to make cuts when the service needed £35m.
The service responded to the claims - to be broadcast on Tuesday on BBC Wales' Week In Week Out - saying it is working exhaustively on modernisation.
Health Minister Brian Gibbons said he was committed to providing a "world class ambulance service".
Roger Thayne was brought in as a trouble shooter two months ago but he said what he found were shocking failures in the service.
Mr Thayne had written a damning report cataloguing outdated equipment, a history of poor management and delays in getting ambulances to patients - contributing to a service he claims is dangerous.
After just eight weeks in his job, he resigned 12 days ago saying he could not stay because he felt ashamed and he did not want to be accountable for a service that was failing so badly.
"I think matters came to a head for me when, despite the poor clinical performance and the poor response performance in my report, it was decided that what was more important was this financial deficit and therefore we should devise a financial recovery plan," he said.
"I really hadn't come to Wales to do a financial recovery plan, I had come to Wales for a patient recovery plan, and to turn the Welsh Ambulance Service around to look after patients better."
He has told BBC Wales's Week In Week Out programme that £35m is needed to make radical reforms.
Thayne said paramedics had to work with out-dated equipment
Dr Gibbons said targets had been set for the service and he accepted capital investment would be needed to achieve them.
However, he added that like other parts of the NHS, the service had to work within the resources available.
"As we speak there are a wide range of changes taking place in the ambulance service," he said.
"There's no doubt the challenge facing the ambulance service is... a two or three-year job."
Dr Andrew Dearden, chairman of Welsh GP committee of the BMA, had previously said the revelations of the ambulance service "in crisis" had come as "no surprise".
"It's something that's been general knowledge amongst the medical profession for a long period of time. Ambulance waits in Wales can sometimes be as long as six or 10 hours after a GP requests them," he said.
"Unless there is investment and unless there is challenging of these political time targets - which have no clinical basis but just politicians picking numbers out of the air ... unless, we challenge those then actually the situation is going to get worse not better."
The trust said its new interim chief executive, Anton Van Dellen, was working on a final version of a modernisation agenda to be presented later this month.
Dr Gibbons said change cannot be rushed
He said: "We've got a very good staff, they are very committed, very well trained, probably the best trained ambulance staff in the UK.
"We are also fortunate that we've carefully worked out what needs to be fixed and it's primarily infrastructure - It's buildings, it's vehicles, medical equipment and it's the technology that we use to tie everything together.
The chairman of the ambulance trust declined to be interviewed.
Week In Week Out is broadcast on BBC One Wales at 2235 BST on Tuesday.