Health chiefs yesterday insisted that an overhaul of out of hours medical cover would cope with patient demand - despite fewer GPs on call to treat people.

Health chiefs yesterday insisted that an overhaul of out-of-hours medical cover would cope with patient demand - despite fewer GPs being on call to treat people.

Details began to emerge yesterday of how the new system will operate when it is introduced on August 20.

The service across the county, with the exception of Yarmouth, is to be restructured as part of a new contract between Norfolk Primary Care Trust and the East of England Ambulance Service.

A snapshot of the level of cover under the new contract suggests that, over the busiest weekend period, overall GP cover across Norfolk could drop from 24 doctors to 15, but the number of nurses on call will double from five to 10.

But bosses insist the changes have been designed to ensure that patients have access to treatment.

Scott Turner, assistant medical director at the East of England Ambulance Service, said the service had built up a detailed picture of the peaks and troughs of demand for cover over the last three years.

He said the new centralised triage system would allow staff to prioritise cases, while future plans would see closer working with hospital accident and emergency departments.

Other changes suggest there will be cuts to some shifts in the numbers of emergency care practitioners (ECPs) - specially trained paramedics who can carry out some treatments and admit patients to hospitals.

On a typical weekday night, GP cover would also drop from 10 doctors to six; in the early hours the number of GPs on call is set to remain at four, though cover is likely to be tweaked across the shift patterns to meet demand patterns in the months following the launch of the service.

Many of the changes have been driven by cost-cutting by the debt-ridden Norfolk Primary Care Trust, which awarded the £5.2m contract in May.

But Mr Turner said: "We think the resources are enough and we will be able to marshall those resources around the county so we can arrange cover appropriately.

"In our three years of running the service we have got a robust set of data. We have a strong belief that we will still have adequate resources to cover Norfolk.

"Wherever possible, if the patient is mobile and if their condition allows it, we would like them to come to a base," he added. "If you have clinical staff travelling long distances between calls, that's time which isn't being used clinically.

"Obviously the ECPs are not doctors and it would be wrong to say that they, but they can make a diagnosis and treat admit patients. They can also talk to a doctor on the phone or go out a doctor for a second visit if need be."

But disquiet among some doctors had been growing over fears that the new system would lead to a poorer service for patients while some GPs had also claimed that they had been kept in the dark about the new service.

Under the new system patients will be assessed centrally over the telephone by a doctor or nurse based at the ambulance control room, near Norwich.

About 45pc of callers could be dealt with over the phone while during the week other patients would be referred to centres in Norwich King's Lynn, North Walsham and Thetford, which will be open until 11pm.

Three mobile units, covering the northern, southern and central parts of the county would operate in the early hours and staff manning these would be expected to return to their nearest base to treat patients when not making home visits.

At the busier weekend periods there will also be daytime openings of centres at Fakenham, Dereham, and Diss.

Plans are also afoot to move the Norwich out of hours primary care centre from the former West Norwich hospital site near to the Norfolk and Norwich's accident and emergency department.

David Russell, spokesman for the East of England Ambulance Patient and Public Forum, said: "What we are concerned about is that people will get fed up waiting and phone an ambulance. They have increased the travelling time by 50pc. I live in a seaside village and some people don't have a car.

"We believe if it isn't broken don't fix it, but we know the reasons behind it, the terms have been dictated by Norfolk PCT not the ambulance service. We will certainly be watching them and carrying out an inspection in November."

Meanwhile, the ambulance service also insisted that doctors had been officially notified of the changes in letters sent on July 5 and again on July 17, while those taking part in the scheme were told how they could book shifts.

Posters to be displayed in surgeries, patient leaflets and a list of frequently asked questions were also sent out on July 25.

A secure website had also been set up allowing for doctors signed up to the scheme allowing them to check the availability of the new service and look at shift patterns.