Labour could merge police forces and axe police and crime commissioners as part of a drive to save money on public services if it wins power, according to a senior party Treasury spokesman.

Chris Leslie will use his first major speech as shadow chief secretary to the Treasury to say that a L abour government would reform and reconstitute public services to release "cashable savings" to the Exchequer.

Mr Leslie is expected to attack "botched" reforms under the coalition, which he claims have cost the taxpayer billions of pounds without delivering improvements to public services.

Following shadow chancellor Ed Balls's pledge last month that a Labour government would achieve a current budget surplus by the end of the next parliament, Mr Leslie will say that the centre-left must embrace the goal of balancing the books because "the foundation of successful public service provision is the sound stewardship of public finances".

The party's ongoing "zero-based review" of all items of government expenditure aims not only to improve outcomes for service users but also to deliver efficiencies and save money by "decluttering" the way services are delivered, Mr Leslie is expected to say.

"Long-term and sustainable budget savings can only be made if we think and reform public services while delivering standards that people need and expect," he will tell the Social Market Foundation think-tank in London. "We are looking not only at where efficiencies are achievable, but how services could be reconstituted to release the cashable savings that are now required."

Labour is currently consulting on proposals from the independent Stevens Commission, which last year recommended mergers to reduce the 43 police forces in England and Wales as well as the abolition of directly-elected PCCs, introduced by the coalition Government in 2012 to replace police authorities in 41 areas.

A previous attempt to merge police forces under Labour's former home secretary Charles Clarke was abandoned after sparking widespread controversy.

As well as locally-negotiated force mergers, other cash-saving ideas being considered by Labour include creating "leaner and more efficient" commissioning processes for health and social care, relocating magistrates and county courts into single buildings, encouraging emergency services to share premises and telling local councils to share senior staff and services, Mr Leslie is expected to say.

He will contrast Labour's plans with the coalition Government's reforms - including the reorganisation of the NHS and the introduction of universal credit, free schools and the Work Programme - which he will say have ended up wasting money.

"Reform is worse than pointless if it does not improve the experience of the user and ends up costing money rather than saving money", Mr Leslie is expected to say.

A Conservative spokesman said: "'This is just the same old Labour: they did two 'zero-based spending reviews' in government but still took us into the financial crisis with the biggest structural deficit in the developed world.

"The most important thing now is to stick to our long-term economic plan. We can see that plan is working - the economy is growing, the deficit is down, jobs are being created.

"Sticking to this plan is the only way to deliver more economic security for families and a better future for Britain."