British police arrested six former News of the World journalists on Wednesday in a new probe into alleged phone hacking at Rupert Murdoch's now-closed tabloid, Scotland Yard said.
Investigators had identified a "further suspected conspiracy" at the paper in 2005 and 2006 which was separate to the alleged hacking under which a number of people have already been charged, it said in a statement.
Two of those arrested on Wednesday now work at the daily tabloid The Sun, according to an internal memo by the chief executive of News International, the British newspaper wing of Murdoch's US-based News Corp. empire.
British media named the two Sun journalists as Rachel Richardson and Jane Atkinson, and the other four detainees as former assistant editor Jules Stenson, former features editor Matt Nixson and former showbiz editors Rav Singh and Polly Graham.
The News of the World closed in disgrace in 2011 amid allegations that it had hacked the mobile phone voicemails of hundreds of celebrities, politicians and victims of crime and terrorism.
"Detectives on Operation Weeting have identified a further suspected conspiracy to intercept telephone voicemails by a number of employees who worked for the now defunct News of the World newspaper," Scotland Yard said.
"As part of the new lines of inquiry six people were arrested this morning on suspicion of conspiracy to intercept telephone communications... All of them are journalists or former journalists."
Police said they arrested three men aged 46, 39 and 45, two women aged 33 and 40 in London, and a 39-year-old woman in Cheshire, northwest England, and were questioning them at various police stations.
Searches were also under way at a number of addresses.
"In due course officers will be making contact with people they believe have been victims of the suspected voice mail interceptions," police added.
News International declined to comment on the arrests.
But in an internal memo to staff, News International chief executive Mike Darcey said the two Sun staff members were being offered legal assistance, a source told AFP.
Those already facing trial over hacking at the News of the World include British Prime Minister David Cameron's ex-spokesman Andy Coulson and Rebekah Brooks, the former head of Murdoch's British newspaper wing.
Operation Weeting was launched in January 2011 to investigate a string of allegations over hacking at the weekly News of the World, which was Britain's biggest selling newspaper.
Since then News International has paid out millions of pounds in damages to hacking victims.
Last week Sarah Ferguson, the ex-wife of Britain's Prince Andrew, won undisclosed damages, as did singer James Blunt, Israeli entertainer Uri Geller, and actor Hugh Grant.
Others to win damages over the past two years are actors Jude Law and Sienna Miller, England footballer Ashley Cole and former deputy prime minister John Prescott.
Two other police enquiries sparked by the events at the News of the World -- into the bribery of public officials and the hacking of emails -- are also under way.
The scandal also prompted Cameron to launch a judicial inquiry into press ethics -- the Levenson Enquiry -- which in its conclusions last year called for a new, tougher watchdog for the press, backed by legislation.
A deal on the new regulator is nearing completion this week, although it is likely to be overseen by a royal charter -- a special document used to establish and set out the terms of organisations including the BBC and the Bank of England -- rather than by law.