The police watchdog has launched an investigation into allegations that a senior Scotland Yard officer inappropriately passed information to a News International executive.
The Independent Police Complaints Commission (IPCC) said it was examining contacts between the officer, believed to be of superintendent rank, and the executive during the original 2006 investigation into phone hacking at the News of the World.
Investigators are looking at whether the information provided was legitimately in the public domain.
The IPCC will consider whether the officer committed a criminal offence or may have a case to answer for misconduct.
At this stage there is no evidence to suggest that any inappropriate payment of any kind was made to the Scotland Yard officer, the watchdog said.
The IPCC launched the inquiry after a referral on February 7 by the Metropolitan Police's Operation Elveden team, which is investigating alleged corrupt payments to public officials by journalists.
The watchdog will co-ordinate its work with the ongoing Leveson Inquiry into press standards, which resumes on Monday with evidence about relations between journalists and the police.
IPCC deputy chair Deborah Glass said: "In this case, the allegation of an inappropriate disclosure of information from an MPS (Metropolitan Police Service) officer to an executive at News International raises important issues of public confidence in the MPS and I believe it is right that we independently investigate this to determine if there was any wrongdoing.
"The Leveson Inquiry is, among other things, inquiring 'into the way in which any relevant police force investigated allegations or evidence of unlawful conduct by persons within or connected with News International', and I will therefore be liaising with them on the extent to which the IPCC should explore the consequences of any inappropriate contact."
Scotland Yard said it had decided not to suspend the officer, who is based within the force's specialist operations branch, which is responsible for counter-terrorism and protecting the Royal Family and other dignitaries.
The officer under investigation is believed to be of superintendent rank.
The Met's original phone-hacking inquiry resulted in the jailing of News of the World royal editor Clive Goodman and private investigator Glenn Mulcaire in January 2007 after they admitted intercepting voicemail messages left on royal aides' phones.
Ten current and former senior reporters and executives at The Sun, the News of the World's sister paper, have been arrested since November as part of Operation Elveden.
The phone-hacking scandal led to the closure of the News of the World last July, and the resignation of Metropolitan Police Commissioner Sir Paul Stephenson and Assistant Commissioner John Yates.