It is part of an investigation into the awarding of a number of PSNI vehicle contracts.
Four men were arrested in Northern Ireland in counties Antrim, Down and Tyrone.
Two men were arrested in England and are being brought to Northern Ireland for questioning.
The suspects were arrested on suspicion of a range of offences including bribery, misconduct in public office and procuring misconduct in public office.
Those arrested in Northern Ireland include a 48 year old police officer, a 37 year old member of police staff, a 54 year old former police officer and a 62 year old civilian.
The two civilians arrested in England are aged 34 and 54. A number of searches at residential and business premises were also carried out and several items have been seized.
The suspects have been taken to the Serious Crime Suite at Antrim police station for questioning.