HP is cutting 1,124 jobs in the UK next year as part of its downsizing operations.
The Unite union said that more than 600 jobs could be lost in Bracknell, with almost 500 to go in Warrington and 23 in Sheffield, reports BBC.
However, HP has said that not all 1,124 employees will leave the firm - it said some would get new roles within the company as it hires new staff.
HP previously announced it would cut 27,000 jobs worldwide by the end of 2014.
The vendor is said to currently employ more than 15,000 people in the UK.
HP said in a statement: "HP remains committed to supporting the employability of its employees through a number of internal initiatives, including re-skilling, redeployment and support to obtain alternative employment as appropriate."
Unite's national officer Ian Tonks added: "For the last five years, HP has been addicted to a culture of job cuts in the UK to such an extent that its highly skilled workforce has little faith in the way the company is being managed and will be, going forward.
"Unite will be doing everything possible to mitigate these job losses, which are a hammer blow to the UK's IT sector and very distressing for employees in the run up to Christmas."
HP CEO Meg Whitman previously said that fiscal 2014 will be a "pivotal year" for the firm, and is pleased with HP's turnaround and falling debt.