A construction contract that cost Herefordshire Council double the original estimate was awarded without a tendering process, a report has found.
The authority was not kept informed the refurbishment of council offices at Blueschool House, by Kier, would be almost £1m over budget, it said.
Officers made decisions, including signing off money, without being overseen by a board and councillors.
The Conservative-led council has apologised unreservedly.
Blueschool House, in Hereford, where JobCentre Plus, Home Point and Housing Solutions are also based, reopened on 4 September after costing £970,000 more than originally thought.
Councillors approved the overspend in July and they said the project identified weaknesses in the planning and monitoring of property costs and an internal audit would be carried out.
The report found officers acting without authority, with one approving £319,000 in compensation without approval.
Although Kier and Balfour Beatty Living Places were able to carry out the work, the report said: “There appears to be no clear evidence to support how the decision to select Kier was made”.
Overall the report found key staff, including senior directors, “have knowingly disregarded council process and procedure”.
Anthony Powers, leader of It’s Our County, said: “We knew this situation was bad.
“We knew that there were other examples of procurement and management that were bad too. What we have now learned is that this was and is a catastrophe.”
A council spokesman said it failed to offer Herefordshire residents value for money.
“It is disappointing for us all to find that some colleagues, however small in number, did not observe the correct procedures.”
The council’s audit and governance committee has asked for an external audit to be carried out.
Kier has been asked by the BBC for a response.
Source: BBC Here