Corby Council has been threatened with legal action by architects Hawkins Brown over the contents of the Cube report.
The firm has asked that the report be taken down from the council’s website and has given the authority seven days to respond.
Acting chief executive of Corby Council, Norman Stronach, said: “We received a letter late on Tuesday, August 8, from Clyde and Co Solicitors acting for Hawkins Brown, the Corby Cube architects.
“The letter takes issue with the Cube report in terms of accuracy, fairness and partiality. They consider the report to be defamatory to Hawkins Brown and have asked for the removal of the report from the website and a full retraction.
“They give the council seven days to respond, reserving the right to take action to recover damages in respect of this publication.”
Mr Stronach said the borough council has sought external expert legal advice on the letter.
A version of the scrutiny report into the escalating cost of the Cube in Corby was made public last month.
Commissioned at the request of councillors who were concerned at the mounting cost of the civic hub, it reported that an additional £11.8m was needed on top of the £35.3m which had already been spent on the building, which houses Corby’s library and The Core theatre.