The changes could prompt industrial action

The PCS said it was "shocked" by the cull and warned that pensioners and people on benefits would suffer.

Work and Pensions Secretary Andrew Smith says he regrets job losses but argues savings are necessary to help tackle child and pensioner poverty.

Chancellor Gordon Brown said last year 40,000 civil service jobs would go.

As well as the loss of 550 benefit offices, 10 pension centres will also close with the Department of Work and Pensions bearing the brunt of the redundancies.

Up to 10,000 jobs will also go at the Inland Revenue and Customs, and more than 1,000 from the Department for Education and Skills.

Mr Brown announced the job losses in last year's Budget speech.

'Impact on services'

The PCS said the processing of benefits such as income support and jobseekers allowance would move from 650 sites to 100 centres - ending a local service.

Pension centres in Plymouth, Burnley, Wrexham, Stockton, Wolverhampton, Nottingham, Norwich, Derby, Liverpool and York will close.

PCS general secretary Mark Serwotka said: "To think you can arbitrarily slash thousands of essential jobs without any adverse impact on the delivery of services is the height of naivety.

"The pension service and access to benefit advice will be decimated by these proposals, denying local access to services for thousands of pensioners and some of the most vulnerable in society.

"These cuts will impact on every community in the UK, damaging services and local economies and putting hard-working public servants on the dole."

Industrial action?

Mr Serwotka urged ministers to rethink their plan and warned the cuts would have a "devastating impact".

He said the union was considering "all options" to defend jobs.

The PCS has already threatened industrial action in protest at the job losses.

Those affected by the cuts were being told on Tuesday.

They will be offered support from the government's Jobcentre Plus services.

'Last resort'

Mr Smith said: "While any job losses are regrettable, improving efficiency will release resources to make further progress on child and pensioner poverty and get even closer to full employment."

Modern technology and improved processes meant more cash would be given to the frontline as part of a bid to boost efficiency.

The DWP's top civil servant, permanent secretary Sir Richard Mottram, said: "DWP is committed to one of the largest change programmes in Europe over the next four years and beyond. It will inevitably be unsettling for our staff.

"Staff in areas directly affected will get more detailed information face-to-face from their managers."

The cuts would be implemented through staff redeployment, voluntary release schemes and the "last resort" of compulsory redundancy.