More than 10pc of life-threatening calls in Norfolk and Suffolk were downgraded by the region's ambulance service last year, according to new figures.

The East of England Ambulance Service received a total of 74,724 'red' calls in 2012 across the two counties, but downgraded 7,840 of those.

Officials at the NHS trust said that the process of downgrading calls, which began in October 2011, was started to try and ensure responders and paramedics reached those most in need.

Figures obtained by the EDP under a Freedom of Information (FoI) request show that the ambulance service, which covers the six counties of Norfolk, Suffolk, Cambridgeshire, Essex, Hertfordshire, and Bedfordshire, downgraded 9.7pc emergency calls last year. However, in Norfolk it downgraded 11pc of red calls and 9.6pc in Suffolk.

The trust is required to respond to 75pc of 'red' calls within eight minutes and 95pc within 19 minutes to hit key performance targets. However, the trust can take up to an hour to reach an incident, if it downgrades the call to 'green'.

The FoI results show that out of 42,395 emergencies in Norfolk last year, 4,726 were reduced to green incidents and ten were upgraded. In Suffolk, 3,114 out of 32,329 calls were downgraded, with just two being upgraded.

A spokesman for the East of England Ambulance Service said common call downgrades occurred when a patient phoned up suffering from chest pains, but were found to have no other symptoms. Calls relating to a person who was not alert were downgraded after the person was found to be drunk following further investigations.

Following an initial assessment by a call handler, the trust's Enhanced Clinical Triage team focus on some 'red' events before the arrival of a responder or paramedic and re-categorise if necessary.

The spokesman said: 'While the call assessment system we have in the control rooms is used around the world and pinpoints the most critical calls, there are limitations in accurately assessing patient needs in the next category, so it errs on the side of caution. This means further triage by a nurse or advanced paramedic is extremely useful in making sure patients who need to take precedence are still given priority. Of course, given the quality of information from the call maker, and any subsequent information they or another person gives, we react as quickly as we can to ensure we're sending the right response.'

The East of England Ambulance Service launched its Right Call campaign last year to explain to people how they assess and respond to calls.

Director of operations Neil Storey said: 'Our staff deal with thousands of calls each week, but for one person it might be the only 999 call they make in their lifetime. We want to make it clear to them about what to expect, why a call is being handled in a certain way, and to even think about alternatives to 999.'

The trust is currently only reaching 93pc of A19 incidents in 19 minutes and in Norfolk and Suffolk that figure is below 90pc.

For more information about Right Call, visit www.eastamb.nhs.uk