Public sector bodies are still wasting taxpayers’ money by failing to co-ordinate the way they buy products and services, spending watchdogs have said.

Efforts to better harness bulk buying power had led to some improvements but were not ambitious enough, the National Audit Office (NAO) and Audit Commission (AC) warned.

Their research found some parts of the public sector paying more than twice as much as others for the same type of paper and 169% more for computer monitors.

And there was an astonishing variation in the amount spent on toner cartridges - some costing more than seven times as much as the cheapest.

The watchdogs looked at spending on eight areas such as office equipment, travel and food across Whitehall, local government and the NHS last year.

But although efforts by the Office of Government Commerce (OGC) had led to “real improvements” the system remained “fragmented, with no overall governance”, they said.

There were more than 50 professional buying organisations as well as individual public bodies involved in procurement, leading to 2,500 unnecessary tendering exercises.

NAO head Amyas Morse said: “The public sector spends £220 billion a year on goods and services. Given the potential to make significant savings, it is vital that there is much better co-ordination of procurement activities to ensure value for money is secured across the public sector.”

And Eugene Sullivan, chief executive of the Audit Commission which oversees local bodies, said: “With all public service costs under pressure, better procurement provides an opportunity to make significant savings that don’t cut into front line services.

“Most councils already collaborate but, even where there is collaboration, it is not delivering all the possible benefits”.