A serving police officer and three men have been arrested over payments to police officers.
The 29-year-old male officer was arrested at a police station in central London where he works and three men, aged between 48 and 56, were detained after police swooped on their homes, Scotland Yard confirmed.
The suspects were arrested under Operation Elveden - which runs alongside the Operation Weeting hacking inquiry.
Officers 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.
The three other 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.
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.
Officers made the arrests between 6am and 8am this morning.
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."
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.
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."