British police arrested six current or former journalists on Wednesday in a new probe into alleged phone hacking at Rupert Murdoch's now-closed News of the World tabloid, Scotland Yard said.
Investigators had identified a "further suspected conspiracy" by staff at the paper in 2005 and 2006 which was separate to the alleged hacking under which a number of people have been charged, it said in a statement.
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," the statement 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 arrested three men aged 46, 39 and 45 and 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, the statement said.
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 voicemail interceptions," the statement said.
British media reported that two of those arrested now work for Murdoch's daily tabloid The Sun.
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.