A 37-year-old member of the PSNI staff arrested on Tuesday as part of a police corruption investigation was released yesterday evening pending a report being sent to the Public Prosecution Service.
In the meantime the official has been suspended from duty, the PSNI said in a statement.
Varying periods of additional time have been granted to serious crime branch detectives to continue questioning five other men arrested on Tuesday in Northern Ireland and in England.
The suspects were arrested on suspicion of a range of offences including bribery, misconduct in public office and procuring misconduct in public office.
One is a former high-ranking PSNI officer. Another serving police officer and two other men also remain in custody in Antrim police station while two men are being questioned in England.
As part of this continuing investigation into alleged corruption over PSNI vehicle contracts, a 71-year-old man was detained in Co Down yesterday on suspicion of bribery and procuring misconduct in public office. He remains in custody.
At the time of the arrests a police spokesman said the PSNI expected its officers and staff to behave professionally, ethically and with the utmost integrity at all times.