Five people have been arrested over payments to police officers in the phone-hacking inquiry, Scotland Yard said.
Questioned by detectives are a serving police officer and four current and former employees of The Sun newspaper.
The suspects were arrested under Operation Elveden - which runs alongside the Operation Weeting hacking inquiry.
The Guardian is reporting that the four Sun employees arrested are believed to be "Mike Sullivan, the Sun's crime editor, the former managing editor Graham Dudman, the executive editor Fergus Shanahan and Chris Pharo, a news desk executive."
The 29-year-old male officer was arrested at a police station in central London where he works and four men, aged between 42 and 56, have also been detained, Scotland Yard confirmed.
Detectives are searching the offices of News International in Wapping, east London, and the home addresses of the suspects, a spokesman said.
The officer, who serves with the MPS Territorial Policing command, is being questioned at a south London police station.
He was arrested on suspicion of corruption, misconduct in a public office and conspiracy in relation to the offences.
Three men, a 48-year-old from Essex, a 56-year-old from Essex, and a 48-year-old from north London, were all arrested at their homes.
Officers made the arrests between 6am and 8am today.
A fourth man, aged 42, was arrested at 11am when he attended an east London police station.
They are being questioned at police stations in London and Essex on suspicion of corruption, aiding and abetting misconduct in a public office and conspiracy in relation to the offences.
A Scotland Yard spokesman said: "Today's operation is the result of information provided to police by News Corporation's management and standards committee.
"It relates to suspected payments to police officers and is not about seeking journalists to reveal confidential sources in relation to information that has been obtained legitimately."
In a statement, News Corporation, the parent company of News International which owns The Sun and The Times, said: "Metropolitan Police Service officers from Operation Elveden today arrested four current and former employees from The Sun newspaper.
"Searches have also taken place at the homes and offices of those arrested.
"News Corporation made a commitment last summer that unacceptable news gathering practices by individuals in the past would not be repeated.
"It commissioned the Management and Standards Committee (MSC) to undertake a review of all News International titles, regardless of cost, and to proactively co-operate with law enforcement and other authorities if potentially relevant information arose at those titles.
"As a result of that review, which is ongoing, the MSC provided information to the Elveden investigation which led to today's arrests."
Elveden was launched after officers were handed documents suggesting News International journalists made illegal payments to police officers.
Others questioned as part of the inquiry include former News International chief executive Rebekah Brooks, ex-Downing Street communications chief Andy Coulson, former News of the World managing editor Stuart Kuttner, the paper's former royal editor Clive Goodman, former News of the World crime editor Lucy Panton and Sun district editor Jamie Pyatt.
Mrs Brooks and Mr Coulson are both former editors of the News of the World, which was closed in July at the height of the hacking scandal following revelations that murdered teenager Milly Dowler's phone was involved.
Sir Paul Stephenson, the then Met Commissioner, said in July that evidence from the publisher suggested a small number of officers were involved.
The phone hacking scandal led to the closure of the News of the World after 168 years, prompted a major public inquiry, and forced the resignation of Sir Paul and assistant commissioner John Yates.
Deborah Glass, deputy chair of the Independent Police Complaints Commission (IPCC), which is supervising the investigation, said: "It will be clear from today's events that this investigation is following the evidence.
"I am satisfied with the strenuous efforts being made by this investigation to identify police officers who may have taken corrupt payments and I believe the results will speak for themselves.
"By supervising this important development in Operation Elveden, the IPCC is providing crucial independent oversight in what is a complex criminal inquiry - not just into allegations of corruption against police officers, but allegations involving members of the media.
"I have considered the IPCC's role and whether to use our powers more directly and in this particular instance, given the interlocking nature of the investigation and arrests which do not just involve police officers, I believe the priority is not around whose powers should be used, but for an effective investigation that brings wrongdoers to justice.
"While we continue to provide a supervisory role across Operation Elveden, I will consider each referral on its own merit and we will investigate independently if appropriate."
The arrests bring the number of people questioned in the Elveden investigation to 14. Scotland Yard has arrested 13 suspects and the IPCC has arrested one.