The cost of Galway City Council's plan to move to Crown Square in Mervue is being described as "spiralling out of control".
Councillor Alan Cheevers says a recent briefing has made it clear the cost of fitting out the building will be enormous.
The full move was initially projected to cost around €56m overall - between the cost of the building at €45m, and the rest for the fit-out.
But Councillor Cheevers says they've now been officially told that the fit-out cost has "exploded" due to construction inflation- and he believes it'll possibly add up to 30 million euro.
He's demanding that every single new tender is analysed and that two independent valuations of the building are sought immediately.