Nine 999 vehicles disappeared from Norfolk and Suffolk's roads at a time when the region's under-performing ambulance service was pledging to deploy more emergency vehicles, it has emerged.

Campaigners spoke of their disappointment last night after it was revealed that the number of double staffed ambulances (DSA) covering the two counties was reduced under the East of England Ambulance Service's controversial rota redesign that began earlier this year.

The interim chief executive of the NHS trust pledged to place 15 extra ambulances on the region's roads in February and promised an additional ten DSAs following the unveiling of the service's turnaround plan in April.

However, a redesign of staff rotas and vehicle deployments, which was completed in April, resulted in the number of DSAs in Norfolk and Suffolk being reduced from 53 to 44 - a net loss of nine- figures from a Freedom of Information request show.

The number of rapid response vehicles was reduced from 34 to 31 in Norfolk and Suffolk.

However, an extra 11 Intermediate Tier Vehicles (ITV) have been added to the non-emergency fleet from seven to 18 as part of the restructure in the two counties. Cambridgeshire received a net gain of one extra DSA.

Officials from the East of England Ambulance Service said they were planning to increase the number of ambulances in Norfolk and Suffolk when a clinical capacity review is complete.

Ambulance stations in Norwich, King's Lynn, and Cromer have seen an increase in DSA numbers as a result of the changes. However, Diss, Ipswich, Sudbury, Wisbech and Thetford stations have experienced a decrease in ambulances and at the trust's Waveney depot in Gorleston, DSA numbers have been slashed from 11 to five.

Peter Aldous, MP for Waveney, said the number of complaints he had received from constituents about the East of England Ambulance Service had reduced dramatically since last year. However, he would be seeking reassurances about the ambulance cut in Waveney when MPs receive an update from officials from the trust next month.

'The reduction in the number of DSAs and the shortage of paramedics is one of the major problems the trust has. The reduction in coverage is a cause for concern and it is one I will be seeking an explanation on when I meet Geoff Harris [interim chairman] in September,' he said.

Andrew Morgan, interim chief executive of the ambulance service, announced in February plans to deploy 15 extra DSAs in the region, including at stations in Cromer, Dereham, Diss, Downham Market, Potter Heigham, Beccles and Mildenhall. However, it soon emerged that the trust did not have enough staff to man them.

Norman Lamb, North Norfolk MP and health minister, said: 'The announcement of 15 extra ambulances seems to be a PR disaster. We have been told that there will be a fleet of new ambulances and resources are being shifted from cars to ambulances, but the proof of the pudding will be in the eating and these figures are very disappointing and suggest that they are not yet progressing,' he said.

Between April 2011 and August 2012, the East of England Ambulance Service shelled out £12.8m on private ambulance cover. But the trust has pledged to find £20m of savings to reinvest in front-line services.

The NHS trust has come under criticism from patients, MPs and commissioners over the last year because of slow response times and has been told to improve performance by the Care Quality Commission.

Denise Burke, of the Act on Ambulances campaign and prospective parliamentary candidate for North Norfolk, who met with Mr Morgan last week, said it was 'really disappointing' that ambulance numbers had been reduced in Norfolk.

'This is really disappointing, but I am not surprised. It is wrong that we had promises made to build public confidence. I think the public has been sold short. It makes you wonder what you are being told is fact. These figures show that they have borrowed off Peter to pay Paul,' she said.

A spokesman for the ambulance trust said they had recruited 160 of the 350 front-line staff they pledged to hire in April.

'A full review of deployment areas will be undertaken when the clinical capacity review is complete in October and the rotas will not be reviewed until our clinical capacity review has been completed.'

'The 15 ambulances are being covered by overtime at present so technically in operations until the recruitment phase to fill vacancies is sorted. The trust is putting back in £20m into operations which will help fund these extra resources,' the spokesman said.