Financial watchdogs say they are "baffled" by proposals to build a new Library of Birmingham for £193 million and have warned the high-profile project could turn out to be a financial disaster on a par with the Scottish Parliament.
Members of the city council audit committee said they were far from convinced by the business case for the Centenary Square library and doubted whether the scheme could be delivered on time and on budget.
Critics likened the library to the Scottish Parliament in Edinburgh, where costs soared from £50 million at the planning stage to £414 million by the time the building was occupied.
Mick Wilkes, who when head of the council's scrutiny unit oversaw a damning report into plans for a split site library, said he could not see how the financial estimates for the Centenary Square project added up.
Coun Wilkes (Lib Dem Hall Green) said: "As things stand at the moment, we have no design for this building, no architect and no project manager and it is due to open in six years.
"Yet we are quite specific about costs. This is a point that gives me a little bit of bafflement."
While accepting the need to demolish the existing Central Library in Paradise Forum, which he described as a dysfunctional building, Coun Wilkes said he was far from happy with the proposed replacement.
He warned a promise by the council's leadership to underwrite the cost of the new library could have serious implications for services if the project ran heavily over budget. Other spending priorities could be squeezed if additional funding for the library had to be identified, he said.
"It is a bit much to call this a business case. It is a very poor piece of work," Coun Wilkes added.
Committee member Carl Rice said the launch of the library project last month by council leader Mike Whitby was based on speculative costings.
Coun Rice (Lab Ladywood) added: "I bet this is precisely how the Scottish Parliament started off. I can just see Scottish MPs standing around having this sort of discussion. There is no detailed plan, there is no detailed proposal, it is just aspirational."
The council Labour group believes Centenary Square is the wrong place for the library and would prefer Eastside.
Coun Rice said as many as 10,000 people a day were likely to use the library, which would remain open until 8pm. A clash with revellers using the Broad Street entertainment zone was inevitable, he warned.
"I worry about the logistics of having all these people using the library at the start of the busiest entertainment street in the UK. We will be accused of sour grapes, but it would have been far better to put the library at Eastside," Coun Rice added.
Councillor Kath Grundy (Lab Kingstanding) was concerned that by borrowing £99 million to help fund the library the council would put at risk the remainder of the capital programme. "We are already at maximum borrowing levels now," she warned.
A project manager responsible for overseeing the library is expected to be appointed next month.
Leaders of the council's Conservative-Liberal Democrat coalition insist the finances are sound. Half of the total cost, £99 million, will be met from borrowing, with a further £60 million coming from land sales. A £39 million shortfall is expected to be made up by a combination of grants and private sector contributions, or will be under-written by the council if no other way of acquiring the money can be found.
A spokesman for Coun Whitby said the council leader did not wish to comment on the audit committee's concerns.
Earlier this month Coun Whitby defended the financial calculations after a scrutiny committee member said the library business case appeared to have been "drawn on the back of a beer mat". He said delivering the library would be a priority for the council and he had no doubt that the building would open on time in 2013.
Describing criticism as "facile", Coun Whitby said cost estimates were drawn up by "professional people whose reputations go before them".