A senior Cardiff Labour councillor says plans for a £160m business district in the city centre are under review.
Russell Goodway, whose responsibilities include the local economy, claims the plans outlined last year by the outgoing Lib Dem-Plaid administration were not “founded in substance”.
The proposals, backed by Welsh government cash, aim to boost finance sector jobs in the Welsh capital.
But Lib Dem and Plaid councillors rejected the criticism.
It means he picks up the plans put forward by the previous administration for a major business park in the centre of the city.
Announcing the scheme in March last year, the council said it hoped to attract “blue chip” companies to a central business district (CBD) in the capital and create thousands of jobs, making the area “a powerhouse” for Wales’ economy.
Stretching from south from the train station past Callaghan Square and into Cardiff Bay, the proposals for the site include a convention centre and 4m sq ft of office space.
A revamped bus station nearby would complement Cardiff Central train station to become an “integrated transport hub”.
The council had said it might contribute up to £39m to the project, with the Welsh government adding £21m as part of a wider plan for an enterprise zone focused on financial services.
But shortly after taking office, Mr Goodway has cast doubt on the proposals as outlined by his Lib Dem/Plaid Cymru predecessors, saying the scheme is under review.
He told the South Wales Echo that he questioned whether the project was “founded in substance”.
He told the newspaper: “All the indications I was getting from people who matter – those who will put money into getting the buildings off the ground – was that there was no real prospect of that happening.”
Mr Goodway said he was taking the project “back to the drawing board” and any plans he came up with would be “grounded in reality”.
Plaid councillor Neil McEvoy told the South Wales Echo he was “stunned” by Mr Goodway’s comments and “astonished that he should make such an unjustifiable attack”.
Judith Woodman, who leads the Lib Dem group, rejected an accusation that the plan was electioneering, and told the newspaper the plan was founded in reality.
Cardiff Business School research fellow Dr Andrew Crawley, who published a report on inward investment to Wales in February this year, said Mr Goodway’s comments reflected the economic reality facing those behind the CBD plan.
He said: “Over the last year-and-a-half, in very difficult financial times, it has become very difficult to attract big investment.
“Even though Cardiff council and the Welsh government both have money, it needs to be led by private investment and without an anchor tenant, a big player who is in right from the beginning, it will be very difficult to encourage others in.”
Dr Crawley gave Canary Wharf as an example, with HSBC involved from the design stage of the tower.
He added: “It’s about inspiring confidence. If your anchor tenant is willing to spend money, other people will.
“I still think this could work. It is possible to do something with it but it has to be seen to be led by private money, otherwise it will just be another infrastructure project.”
Chris Nott, interim chair of the enterprise zone board, said his board had agreed to Business Minister Edwina Hart’s request to “co-operate very closely with Cardiff council so as to operate seamlessly”.
He added: “To have an economic development cabinet minister at Cardiff council as experienced and as well connected as Russell Goodway can only have a good impact on this project.”