Bulk buy scheme had 'Alice in Wonderland aspiration'
The body set up to buy goods and services for Welsh public bodies had "Alice in Wonderland aspirations", according to an expert on public spending.
The National Procurement Service (NPS) continues to be bailed out by Welsh ministers after failing to hit targets.
Dermot Cahill, of Bangor University, said public bodies such as councils could get better deals elsewhere.
That was one finding in a report by Wales Audit Office (WAO) in November.
The NPS was established to strike better deals by bulk-buying for the public sector.
When it was set up a few years ago, the expectation was that public bodies across Wales would use it.
But a report from the WAO, the public spending watchdog, found it had only been spending around a tenth of the money that had been envisaged.
Prof Cahill, head of the university's Institute for Competition and Procurement Studies, said the NPS was a "very good idea in principle".
"The idea was that it would be set up to buy once for Wales," he said, explaining that items commonly needed would be bought in bulk by organisation like councils to secure bigger savings.
"But, unfortunately, that was a bit of an Alice in Wonderland aspiration and it hasn't worked out like that."
The NPS has failed to pay back a £5.9m loan from the Welsh Government, which is also using reserves to plug a shortfall in this financial year.
A WAO survey of public bodies about the NPS in 2016 found that some felt it did not provide value for money.
It also found that just 19% of those who took part agreed that using the service resulted in a cash saving. No-one felt strongly that it had led to a saving.
Another concern expressed from organisations was that the focus of the NPS was not geared enough towards local priorities.
In reference to the WAO report, a Welsh Government spokesman said: "The report highlights that public sector expenditure through the NPS agreements is growing year on year.
"In 2016/17 it reached £234m and is on target to exceed that figure in 2017/18.
"The Wales Audit Office report also identifies that the savings generated by the NPS for the public sector exceed the investment in establishing the service."