Four current and former senior Sun journalists and one serving police officer have been arrested as part of Scotland Yard's investigation into police corruption.

The Metropolitan police have also launched a search at News International's headquarters in Wapping, east London, in an attempt to secure any potential evidence relating to alleged payments to police by journalists.

Officers were accompanied by lawyers who arrived at the Sun's offices between 6am and 8am on Saturday morning. They are there to ensure that "journalist privilege" in relation to sources is not compromised.

It is the first time since the phone-hacking scandal erupted that the Sun has been targeted in such a major way, but sources stressed the dawn raid had nothing to do with voicemail interception and was solely related to paying police for stories.

The four Sun employees arrested are understood to be Mike Sullivan, the Sun's crime editor, the former managing editor Graham Dudman, the executive editor, Fergus Shanahan, and Chris Pharo, a newsdesk executive.

The arrests came after information was passed to the police by News Corporation's internal investigations unit, the Management and Standards Committee. It was set up by Rupert Murdoch in the wake of the phone-hacking scandal, which erupted last July, and operates independently of News International.

It is understood that staff and management at the Sun had no warning of the police plans to make arrests or conduct a search of the paper's newsroom.

A statement from News Corp in New York said: "Metropolitan police service (MPS) 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 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.

"No comment can be made on the nature of that information to avoid prejudicing the investigation and the rights of individuals."

The Management and Standards Committee has been charged with ridding the company of old practices and illegal activities such as phone hacking which led to the abrupt closure of the News of the World in July after 168 years. One source said. "They are there to drain the swamp."

In his witness statement to the Leveson inquiry earlier this month, the Sun's editor, Dominic Mohan, said: "To the best of my knowledge, the Sun has never knowingly paid or made payments in kind to police … for information."

Scotland Yard confirmed in a statement that the investigation "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."

It is understood that three of the four journalists were arrested before 8am on Saturday while the fourth was arrested in mid-morning.

"Home addresses of those arrested are currently being searched and officers are also carrying out a number of searches at the offices of News International in Wapping. These searches are expected to conclude this afternoon," the Met said in an earlier statement.

A source said police were interested in everything from "notepads, emails, Post-it notes".

All four men were being questioned at police stations in Essex and London, police said [see footnote]. Fourteen people have so far been arrested under Operation Elveden – 13 by the Metropolitan police and one by the Independent Police Complaints Commission.

The operation is being run in conjunction with Operation Weeting, the Met inquiry into the phone hacking of voicemail boxes.

It was launched after officers were handed documents suggesting that News International journalists made illegal payments to police officers.

Others questioned as part of the inquiry include the former News International chief executive Rebekah Brooks, the ex-Downing Street communications chief Andy Coulson, the former News of the World managing editor Stuart Kuttner, the paper's former royal editor Clive Goodman, the former News of the World crime editor Lucy Panton and the Sun district editor, Jamie Pyatt.

Brooks and 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 the murdered teenager Milly Dowler's phone had been hacked.

Deborah Glass, the deputy chair of the Independent Police Complaints Commission, 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."

• This footnote was added on 1 February 2012 to make clear that the four journalists and the police officer were bailed late on Saturday night, 28 January, pending further inquiries.