Figures presented in an operational performance report for the county show that the equivalent of 31 12-hour shifts were spent by ambulance staff treating patients who could not be admitted to A&E within 15-minutes of arrival.

According to NHS targets, patients should be transferred from ambulances within 15-minutes of arriving at A&E. A total of 125 hours, the equivalent of 10 12-hour shifts, was spent by ambulances waiting in excess of 30 minutes.

The waiting times at Colchester were the highest of the five NHS Trusts within Essex.

The hospital attributed the delays in part to “bottlenecks” when several ambulances arrive at A&E at the same time and a month-on-month rise in the number of people attending A&E.

The number of ambulance handovers over 30-minutes have reduced from 485 hours in January.

A spokesman for Colchester Hospital University NHS Foundation Trust (CHUFT) said: “We are not always able to take over clinical responsibility of patients as quickly as we would like. The number of ambulances arriving here in the three months from April was 9.7% more than the equivalent quarter last year. In addition, the average number of people attending our Emergency Department [is] increasing from a daily average in of 187 in January to 232 in June.

“These are no doubt partly a reflection that Colchester is one of the fastest growing districts in the country in terms of population.

“We continue to work with ambulance service colleagues to minimise the issue of handover delays. What is important is that patients are at all times in the care of either skilled paramedics or specialist nurses and doctors.”

Delays at A&E have a knock-on effect on the number of ambulance response targets being missed. Current targets set by the East of England Ambulance Service state that all incidents should be attended within eight-minutes of a call being received.

While 76% of the most serious “Red 1” incidents were attended within eight minutes in June and 78% so far in July, the number of times the target was missed increased in the two months in six categories, including urgent “Red 2” incidents.

A spokesman for the East of England Ambulance Service said: “Any delay in handing over a patient means that the ambulance is not available to respond to another patient in the community. Other factors include an increase in 999 calls and the need to recruit more ambulance staff in Essex so we can continue to increase ambulance cover.”

Colchester MP Will Quince vowed to make sure that both of these issues are made a priority in the hospital’s improvement plan, set out after the hospital trust was rated inadequate by the Care Quality Commission in April.

He said: “Of course I am concerned with any delays regarding the handover of patients at Colchester General Hospital.

“Patients brought in ambulances can have lift threatening injuries and conditions and we need to ensure that they are being seen as soon as they arrive. This is a significant issue.”

Mr Quince added that he would also be raising the matter with the chief executive of Colchester Hospital University NHS Foundation Trust (CHUFT), Dr Lucy Moore, secretary of state for health Jeremy Hunt and Government minister for health Ben Gummer.