Five policemen have been arrested over allegations they sold contraband alcohol and cigarettes.
The Metropolitan Police officers have also been held on suspicion of money laundering, evasion of liability and criminal misconduct in office.
The men, an inspector, a sergeant, a detective constable and two constables, were arrested following dawn raids at their homes on Tuesday.
Four members of the public from north London have also been arrested.
Scotland Yard's anti-corruption unit is investigating allegations bootleg alcohol and cigarettes from abroad were sold to the public and in police clubs and canteens.
The officers, all from north London, have all been suspended from their posts.
The dawn raids were part of a long-running and on-going anti-corruption operation, a police statement said.
The police officers arrested include a 49-year-old inspector, a 47-year-old sergeant, a 37-year-old detective constable, a 44-year-old constable and a 39-year-old constable.
A 38-year-old woman and a 58-year-old man were arrested on Tuesday on suspicion of evasion of liability and money laundering.
In addition to those arrests, two other members of the public - a 38-year-old woman and a 43-year-old man - were arrested on Thursday, also on suspicion of evasion of liability and money laundering.
All the nine people arrested have been released on bail