Shocked Royal Mail workers last night claimed plans to close Oxford's main sorting office was "payback" for their recent strike action.

Up to 430 employees at the Oxford Mail Centre in Garsington Road face losing their jobs when the office closes in 2009 as part of an "urgent need to improve reliability" in the city.

Union bosses have responded angrily and vowed to fight relocation to Swindon as part of a £20m revamp of services. But workers and managers alike said they were stunned by the move - and were now worried about how they would support their families.

Sorting office worker Kim Curley from Didcot said: "People are shocked.

"I think most of us were stunned, really. There are a lot of couples who work here full time - and it is going to affect them badly. There are people that have been here for 30 years.

"It feels like payback because of the industrial action. They are upset - and their chances of finding another job are pretty slim, I would imagine."

Janice Lewis, from Bicester, has worked at the office for 17 years, while her husband Peter worked as a manager at the depot.

She said: "The mood is like your cat has been run over and your family has all died - it is very gloomy. I suppose we are hoping that it is not going to happen."

Other workers, who asked not to be named for fear of disciplinary action, said they felt "betrayed, shafted and punished" after their roles in several strikes earlier this year.

Industrial relations at the office hit rock bottom following a five-day wildcat strike over the suspension of two workers in July.

A forthcoming ballot for strike action over their subsequent sackings will be followed by more national strikes over pay and working conditions, which will take place over two 48-hour periods, starting on October 5 and October 8. Oxfordshire Communication Workers' Union representative Bob Cullen said there was "no logic" to the plan.

"It's going to lead to an inferior quality of service for the Oxfordshire public with their mail arriving later," he said.

"There was no notice or consultation over this - even the mail centre managers did not know and they were breaking down in tears."

After the shake-up, deliveries will still take place from Oxfordshire, but all mail will be sorted in Swindon.

Royal Mail area general manager Michael Devanny said: "We believe that moving work from Oxford to our extended facility in Swindon will enable us to address an urgent need to improve the reliability of the mail services for our customers in the OX postcode area."

The Royal Mail says that despite mail having to go from Oxford to Swindon and back again, sorting will be 30 per cent quicker thanks to more up to date technology. No decision has been made on the future of the Oxford Mail Centre building on the Oxford Business Park, although it is understood to be leased rather than wholly owned.

Oxford East MP Andrew Smith said: "This is a shock. I am very concerned about job losses and the impact on local postal deliveries.

"I am taking this up with Royal Mail chief executive Adam Crozier and Secretary of State John Hutton. I fear this will pour petrol on the flames of the industrial disputes at the centre."

Claire Prosser, policy executive for the Oxfordshire Chamber of Commerce, said: "Despite electronic communications being a dominant force in today's business climate, the hard copy post is still vital."