Claims that high house prices in Oxford were behind Royal Mail's decision to close the city's main sorting office and relocate to Swindon have been dismissed.

Royal Mail announced last year plans to shut down operations in both Oxford and Reading and spend £20m expanding its sorting office in Swindon to serve the Thames Valley region.

Up to 430 workers at Oxford's sorting office in Garsington Road, Cowley, face losing their jobs, while Royal Mail's workforce in Swindon is set to increase from 400 to 900.

Both local Communication Workers Union (CWU) representatives and East Oxford MP Andrew Smith fear the city's postal service will suffer as a result of the plans - due to be implemented next year.

Last night they also dismissed Royal Mail's claim that one of the primary reasons for investing in Swindon was its low cost of housing, which the company hoped would entice workers from Oxford to relocate.

Mr Smith told the Oxford Mail: "It sounds very much like they're casting around for any reason to justify a decision they have already taken."

He added that he still had grave concerns about the move to Swindon.

He said: "I'm not convinced it makes sense to cart Oxford's mail to Swindon and then bring it all back again - I'm very concerned about the impact on local postal deliveries."

Oxfordshire CWU representative Bob Cullen said Swindon's house prices would do little to entice postal workers to commute or relocate.

He said: "The original plan was for Swindon to be expanded and for Gloucester and Reading to close, but at the last minute they swapped Gloucester for Oxford.

"There's no logic to it and we are totally opposed to the move.

"Housing is cheaper in Swindon than Oxford. But that's nothing to do with it. Swindon was always going to expand and they are determined to close Oxford."

Business pressure group Rox (Rescue Oxford) spokesman Graham Jones added: "The housing issue might be a factor, but I wouldn't have thought it was a major factor."

In a statement explaining its reasons for scrapping Oxford's sorting office, Royal Mail said three-bedroom family homes in Swindon were, on average, £100,000 cheaper than in Oxford, so recruiting staff would be less trouble.

Commercial manager Matthew Lawlor said: "Our staff can embrace a better quality of life as they may be able to have a lower mortgage or an extra bedroom.

"And if we need more staff Swindon has a large workforce with compatible skills, in distribution for example."