Northumbria Police has announced plans to axe more than 1,100 jobs in a bid to tackle budget cuts of £57m.
Over the next two years, 318 officer posts - about 7.75% of the total - will be lost, alongside 825 civilian jobs.
Chief Constable Sue Sim said business reviews had identified ways of putting operational support people back on to the front line.
Unison described the job losses as "astounding", and said it would be seeking a meeting with police bosses.
The force employs about 4,100 police officers as well as 2,500 police staff, special constables and community support officers.
Cuts are to be met by not replacing 318 officers due to retire by 2013.
It has also emerged that since the civilian job loses were announced in November 2010, 365 staff have applied for redundancy.
Chief Constable Sue Sim said: "My commitment is that I maintain the number of people in the response function, in the neighbourhood function, and in our local detective function.
"We have undertaken a series of business reviews which mean we can do business differently and put operational support people back into the front line.
"The police officers are going to be out there where the community want them, doing the job that the community want them to do."
Peter Chapman, from Unison, said: "I am absolutely astounded. The question has to be asked how the force can be sustained with such a loss.
"We have asked for a meeting to explore these issues further."