Police investigating phone hacking at the News of the World arrested a 39-year-old woman in West Yorkshire on Thursday morning.
The woman was arrested just before 7am at a house in the county, Scotland Yard said. She is being questioned by detectives from the Operation Weeting squad investigating the phone hacking scandal.
Scotland Yard said that the woman was arrested on suspicion of conspiring to intercept mobile phone voicemail messages and was being held at a police station in Yorkshire.
Although Scotland Yard would give no further details, a person familiar with the situation said the woman was not a journalist.
News International, parent company of the News of the World, said: “This morning’s events did not relate to a current employee or a former full-time member of staff of the News of the World.
“We have been cooperating fully with the police inquiry since our voluntary disclosure of evidence reopened the police investigation.”
Operation Weeting is the second major inquiry into phone hacking at the News of the World. In January 2007 Clive Goodman, the paper’s royal editor and Glenn Mulcaire, a private detective on contract to Rupert Murdoch’s Sunday tabloid, were jailed after admitting conspiracy to intercept mobile phone voicemails.
At the time, the 15-month police investigation was limited to Mr Goodman and Mr Mulcaire and subsequently News International was adamant that only those two men had been involved in the illegal activities.
But after lengthy reporting by The Guardian and other newspapers, including the Financial Times, News International has conceded that hacking was more widespread and admitted liability in the case of a number of celebrities and public figures.
Police reopened the investigation last December after Ian Edmondson, a senior journalist on the paper, was named in a civil privacy action brought against News International by Sienna Miller, the actress.
Since then, Mr Edmondson has been sacked by the newspaper group and arrested by Operation Weeting officers. Two other men, Neville Thurlbeck, chief reporter, and James Weatherup, a former news editor, have also been arrested and released on police bail.
Scotland Yard was heavily criticised for failing to investigate phone hacking properly and the new team has more than 40 officers working on it.
The scandal spread into the political sphere last year because Andy Coulson, who resigned as editor of the News of the World in 2007 but said he had no knowledge of the illegal activities, had moved on to become a key figure in David Cameron’s inner circle in No 10 Downing Street.
Mr Coulson resigned from that post in January. News International’s own investigation into the scandal and the change in attitude to civil actions launched against it, have been led by its chief executive, Rebekah Brooks, 43.