Departments will today publish their plans for how they will contribute to a £20bn saving on operations spending, the chancellor has announced.

Alistair Darling has told the Commons that the £11bn saving promise set out in the pre-Budget report has been increased to £20bn – and that is before the comprehensive spending review has taken place, he added.

The demands placed on departments by the budget deficit are “tough and challenging, but achievable”, the chancellor said.

He confirmed that key areas of “frontline” work, such as policing, education and health, would be protected from the cuts. There will also be an additional £4bn for Afghanistan, he said, but that will all mean additional savings elsewhere in government.

As well as the cuts to departmental programmes, he said the £20bn saving would come from limits to public sector pay and reform of public sector pension schemes could save the government £4bn.

There will be reductions to the senior civil service salary bill through "reshaping" providing more than £100m in savings, according to the updated 'Smarter Government' paper.

Public sector pay settlements will be limited to a maximum of one per cent for two years from 2011, Darling also said.

The chancellor resurrected the Lyons agenda, promising that one-third of civil service posts currently based in London will be moved out of the capital.

That will mean 15,000 posts in the next five years – including 1,000 posts from the Ministry of Justice in the coming months, he added.

Asset sales will also contribute to the reduction in the budget deficit, he continued, revealing that progress continued to be made on sales of the Tote, the Student Loans Company and the Dartford Crossing. These will make a “significant contribution to reducing debt”.

- News on each departments' plan will follow on Civil Service Live.