Health Secretary Patricia Hewitt has defended NHS services which have been hit by reorganisation, job losses and budget deficits.
The government wants ambulances to get to emergency calls faster
The amount spent on public health care had doubled since 1997, and a "minority" of NHS organisations were in serious financial straits, she said.
It was often because they had taken on staff they could not afford.
Her comments come as reforms cut England's health authorities from 28 to 10 and ambulance trusts from 29 to 12.
Ms Hewitt told BBC Radio 4's Today programme: "We have a minority of organisations, just one in 10, that do have serious financial problems and they are the ones who have got serious financial problems because in some cases they have taken on staff they simply couldn't afford.
"On top of this, we have all kinds of changes in medical technology and the way we look after patients."
The government says the changes to strategic health authorities and ambulance trusts, which came into force on Saturday, will reduce bureaucracy and duplication and release money for better health care and more efficient ambulance services.
But there has been mixed reaction to the changes, with critics saying it will throw the NHS into greater turmoil.
The independent think tank the Kings Fund said it was the right reform at the wrong time.
It said the NHS was already wrestling with a series of other changes and this would throw the service into even greater turmoil.
The move is part of the government's bid to improve the time it takes ambulances to answer calls.
It has just announced extra funding for new control room technology and vehicles in order to help ambulance services reach tougher response time targets.
The strategic health authorities in England which have been merged run health services across the country.
Asked about the problems newly-qualified nurses were having finding employment when they finish their training, the health secretary said the NHS was employing 85,000 more nurses than in 1997.
"Because we've got so many more nurses in posts it is more difficult for new nurses to get jobs," she said.
"What we're doing is working with the hospitals to make sure that everything possible is being done to make sure newly-qualified staff - not just nurses but others as well - do get jobs.
"They may have to travel further, they may have to take a job that isn't exactly what they were hoping for."
But, she said: "The important thing is when you ask patients, for instance patients who were recently in hospital, nine out of 10 are saying thanks to that, due to extra staff, the care they got was good, very good or excellent, which is far better than it was even four or five years ago."