Urgent calls have been made for the region's ambulance service to increase front-line staff numbers after it emerged that the trust had been paying more than £1m a month in overtime for the last year.

The under-fire East of England Ambulance Service spent more than £12m in 2012 as a result of its 4,000 staff working overtime, new figures reveal.

Paramedics and union officials said the figures, obtained by the EDP under a Freedom of Information (FoI) request, demonstrated how over-worked staff needed extra help.

The ambulance service is trying to address high staff sickness levels, hire around 200 more paramedics and emergency care assistants, as well as redesign rotas to improve the performance of the NHS trust, which has been told to address slow response times by health regulator, the Care Quality Commission.

Figures from the FoI show that the East of England Ambulance Service spent more than £1m a month for the last 12 months on staff overtime, which includes emergency, non-emergency, primary care, control room and support staff. Overtime payments peaked this winter when they paid more than £1.2m in January and February, according to the figures.

Tony Hughes, GMB union organiser for the ambulance service, said the trust would reduce sickness rates and raise morale if it could deploy more front-line staff.

'They do not have enough staff to cover the number of calls and they have to pay overtime when crews over run. You see a lot of people claiming two to three hours on the end of each shift and the new crew will be waiting at the ambulance station waiting for the old crew to come back.'

'Sickness levels are appalling because of the pressures they are being put under and the amount of work they are having to do. £1m a month is a lot of money and they need to increase crews substantially. There are positive changes and we need to build on that to make sure the resources are right and staffing is right,' he said.

The ambulance service's rota redesign was completed this week. However, a Norfolk paramedic told the EDP that staff who had been on eight and ten hour shifts were being asked to stay on to do 12 hour shifts to cover staff shortages.

'We seem to lurch from one disaster to another,' the paramedic said.

The East of England Ambulance Service is looking to make efficiency savings of £50m over the next four years. However, the EDP also revealed last month that the trust spent almost £13m between April 2011 and April 2012 on private ambulances.

North Norfolk MP Norman Lamb said: 'It demonstrates how poorly resources are being used. They are spending a fortune on private ambulances, they have huge sickness rates and very low staff morale. This is a question about the deployment of resources and how things are being led and run. It is not a question of needing more resources, but using them more effectively.'

A spokesman for the East of England Ambulance Service said the adverse and cold weather so far this year had put added pressure on the NHS trust.

'The recruitment of more staff, reducing sickness absence levels and working with hospitals to tackle patient handover delays will all help. Alongside this the trust has commissioned a clinical capacity review to understand what resources it really needs to meet patient demand,' he said.