A serving police superintendent continues to be questioned over allegedly passing unauthorised information to a journalist.
The City of London Police officer was arrested by the Independent Police Complaints Commission (IPCC) on suspicion of misconduct in a public office.
He was taken into custody on Thursday after Metropolitan Police officers investigating payments by journalists to public officials passed information to the IPCC.
The continued questioning comes as three people were bailed as part of Operation Elveden, Scotland Yard's investigation into allegations of inappropriate payments to police, which is being supervised by the IPCC.
A 40-year-old man and 37-year-old woman were arrested by officers from Operation Elveden at their homes in Corby, Northamptonshire, while a 31-year-old man was arrested at his home in Croydon, Surrey, a Scotland Yard spokesman said.
The 40-year-old, a former prison officer, was arrested on suspicion of corruption, suspicion of misconduct in a public office and suspicion of money laundering offences.
The woman was arrested on suspicion of aiding and abetting misconduct in a public office and suspicion of money laundering offences.
The 31-year-old man, believed to be a Sun journalist, was arrested on suspicion of conspiracy to corrupt and suspicion of conspiracy to cause misconduct in a public office. They have all been bailed until October.
Operation Elveden, Scotland Yard's investigation into allegations of inappropriate payments to police, began last summer after officers were handed documents suggesting News International journalists made illegal payments to the police.
Elveden is linked to Operation Weeting, the investigation into phone hacking, and Operation Tuleta, a probe into allegations of computer hacking.