A third of the Ministry of Justice's (MoJ) 80,000 staff could see their jobs at risk under plans to cut £2bn from the department's annual budget, a union has warned.

The Public and Commercial Services Union (PCS) has expressed fears that £2bn of the MoJ's £9bn budget will be axed within the first two years of the next spending review, which will be announced on 20 October.

The union fears that 15,000 of the MoJ's 80,000 staff could be at risk of losing their jobs under the cuts, which it says are  the equivalent of the entire budget for prisons.

The MoJ submitted proposals for savings to HM Treasury yesterday (10 August), which has asked all departments to make savings of between 25% and 40%.

MoJ director-general of finance Ann Beasley reportedly informed senior civil servants yesterday of the scale of the savings, alluding to the fact that there will be inevitable job cuts.

PCS general secretary Mark Serwotka said: "This is the first indication of the true scale of the cuts being imposed upon departments by this coalition government, and it paints a devastating picture."

He added: "It is clear that the civil service will simply not be able to cope. We will take every opportunity to remind the government and the public that there is an alternative and these politically-motivated cuts are entirely avoidable."

A MoJ spokesperson said: "The Ministry of Justice has submitted proposals for savings to HM Treasury. Like all departments we were asked to plan for savings of 25% and 40% as part of the coalition Government's deficit reduction plan.

Adding: "We are discussing options with Treasury and will not provide a running commentary on the process. No decisions have been made. The outcome of the spending review will be announced on 20 October."