Six people were arrested Wednesday in what London's Metropolitan Police is calling a separate phone-hacking conspiracy at Rupert Murdoch's defunct News of the World newspaper.
All of them are journalists or former journalists, police said.
Dozens of people, including Murdoch protégé Rebekah Brooks and Andy Coulson, a former adviser to prime Minister David Cameron, already have been arrested and several have been charged with phone hacking and related crimes.
Police say Wednesday's arrests are part of a separate conspiracy to hack phones, primarily from 2005 to 2006, at the News of the World.
Three men and two women were arrested in London and one woman in Cheshire, in northern England.
Searches are being carried out at several addresses, police said.
"In due course officers will be making contact with people they believe have been victims of the suspected voicemail interceptions," a police statement said.
Murdoch closed the Sunday tabloid, one of the world's best-selling English-language newspapers, in 2011 over the phone-hacking scandal.
Three police investigations were created to look into allegations of phone hacking, bribery of public officials and computer hacking.
Brooks and Coulson are both former News of the World editors. Brooks later became chief executive of News International, a UK subsidiary of Murdoch's News Corp. empire. Coulson went on to become Cameron's director of communications before resigning early in 2011.
The hacking scandal prompted Cameron to set up an independent, judge-led inquiry -- named for Lord Justice Leveson, its chairman -- to make recommendations on journalistic ethics and examine the relationship of the press with the public, police and politicians.