A serving police superintendent with City of London Police has been arrested on suspicion of passing unauthorised information to a journalist.
The officer was arrested by the Independent Police Complaints Commission (IPCC) on suspicion of misconduct in a public office.
He was arrested after Metropolitan Police officers investigating payments by journalists to public officials passed information to the IPCC.
In a statement, the IPCC said: "A serving officer of superintendent rank, from City of London Police, has today been arrested by the Independent Police Complaints Commission (IPCC) on suspicion of misconduct in public office.
"The arrest is the result of information passed to the IPCC by the Metropolitan Police Service team investigating Operation Elveden. It relates to the alleged passing of unauthorised information to a journalist. The man is currently in custody at a London police station."
In a separate development, three people were arrested by police investigating allegations of inappropriate payments to police and public officials. A 40-year-old man and 37-year-old woman were arrested in Corby, Northamptonshire, while a 31-year-old man was arrested in Croydon, Surrey.
A News International spokeswoman confirmed that one of the three individuals arrested was a Sun journalist but declined to reveal the person's identity.
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 on suspicion of aiding and abetting misconduct in a public office and suspicion of money laundering offences; and the other man on suspicion of conspiracy to corrupt and suspicion of conspiracy to cause misconduct in a public office.
The arrests bring the number of suspects held in connection with Operation Elveden to 33. Scotland Yard said the arrests are the result of information provided by News Corporation's Management Standards Committee.
Meanwhile, the Crown Prosecution Service said a Guardian journalist who admitted phone hacking will not be prosecuted. David Leigh, the paper's investigations executive editor, admitted hacking an arms company executive's phone. But the CPS said its view was that he should not be prosecuted.