HP employees working on government contracts are at risk of losing their jobs as the coalition considers plans to offshore work to India.
The Public and Commercial Services (PCS) union says that 200 positions could be lost.
HP provides IT support to the Department for Work and Pensions, and the jobs in question are based at sites in Newcastle, Lytham St Annes and Sheffield.
The plans are yet to be finalised and still require ministerial approval, but the union warns that they are at an advanced stage, and jobs would be moved to Bangalore as early as November this year.
The union also argues that offshoring the skills is a false economy, as the savings in IT would be offset by lost tax revenues and increased benefit payments.
"The government must not allow low-paid jobs to be offshored," said PCS general secretary Mark Serwotka.
"It will be a disaster for UK workers and the taxpayer, and will only ensure that HP's shareholders reap the benefits."
PCS is consulting its members about the proposals and has not ruled out industrial action.