The Department for Work and Pensions (DWP) could find itself under pressure next week unless a planned strike by Hewlett-Packard staff is called-off.
The majority of HP workers on contracts with the DWP at sites in Newcastle, Washington, Preston and the Fylde Coast have voted to go on strike on 10 December.
A source told Computer Weekly that one DWP centre has already agreed pre-Christmas holidays for some staff, leaving managers worried that they will not be able to cope if the strike goes ahead.
But HP said in a statement that it does not expect the strike to cause disruption.
"In the event of any industrial action, we would expect minimal interference in service. In cooperation with our clients and the involvement of our company-wide global delivery capabilities, we will take the necessary measures to deliver the services that our clients require."
HP said that out of 914 ballot papers 358 workers voted yes to the strike and 100 voted no. The remaining papers were either not returned or spoilt.
Robert Morgan, director at consultancy Hamilton Bailey, said if HP does not avert a mass walkout it could damage the supplier's reputation for ever.
"In the past there have been localised strikes at suppliers working on contracts, but it has only ever involved a small number of workers. If all the staff go on strike it will be unprecedented," he said.