Emergency call outs may be increasingly dealt with by medics in people carriers rather than traditional ambulances, a senior official says.
The ambulance review will be published next week
The proposal will be put forward in a review of the service by London Ambulance Service boss Peter Bradley for the government next week.
He told the Health Service Journal patients will be dealt with in the field, relieving the pressure on A&E.
The Department of Health said it would not lead to a reduction in ambulances.
The idea is that, instead of ambulances attending all 999 calls, they would be directed to the most serious call-outs.
People carriers, manned by the emergency care practitioners, trained to deal with minor problems, would then deal with the less serious ones.
The proposals, to be phased in by 2011, will enable a million 999 calls to be dealt with in the community rather than in hospital, saving the NHS money.
Mr Bradley said: "We are going to see a big shift from not only providing clinical guidance in the field but also in the control centres, dealing with patients at source rather than elsewhere."
He said in London it could mean as many as half of all calls being dealt with by emergency care practitioners.
Nigel Edwards, director of policy at the NHS Confederation, said it was a difficult area, but the proposals were "grounded in common sense".
"Peter Bradley is taking one of the most visionary approaches to the development of ambulance services in the world.
"Emergency care practitioners are highly skilled and save lives. They can treat people at home who don't need to go to hospital.
"That frees up the ambulances to get the emergency cases into hospital faster."
A Department of Health spokesman said he could not comment on the contents of the review, but added it would not lead to a cut in the ambulance fleet.
"The review proposes to extend the role of ambulance services, not diminish them."