A corruption investigation has been launched by Harrow Council into payments made under two of its biggest building contracts.
The joint probe between the authority and Kier, the construction company that maintains and upgrades the borough's social housing, will examine allegations of the submission of fraudulent invoices and kickbacks, the Observer understands.
Harrow Council leader Councillor David Ashton (Conservative) said: "Harrow Council launched an investigation after several sub-contractors brought allegations of corruption to the attention of a council officer.
"In the course of the council's own investigation which followed, it spoke to two other sub contractors.
"A joint investigation between Harrow Council and Kier is under way. It is important to stress that at present, while serious, these allegations remain unproven.
"However, Harrow Council expects the highest standards of probity from its commercial partners. If any money is found to be owed as a result of these allegations, the authority will look to recoup those losses."