Stoke-on-Trent City Council has suspended six regeneration officers as part of an inquiry into its tendering process for demolition work.
The local authority is being helped by the Audit Commission, which has taken away a number of documents relating to the investigation.
Additionally, police have made one arrest following complaints about the council's approach to demolition procurement.
The six suspended officers all work for the council's Regeneration Directorate.
John van de Laarschot, chief executive of Stoke-on-Trent City Council, said: "The city council is working closely with Staffordshire Police and the Audit Commission on this investigation.
"I will not comment on these suspensions but I want to be clear that I expect officers at Stoke-on-Trent City Council to work to the highest standards of professionalism and integrity.”