A 61-year-old man was arrested in the UK today on suspicion of phone hacking.
Scotland Yard said he remained in custody after visiting a London police station by appointment at midday.
The suspect is understood not to be a serving member of staff at News International.
The arrest by Operation Weeting detectives comes a week after Stuart Kuttner, the former managing editor of the News of the World, was held on suspicion of phone hacking and inappropriate payments to police.
The new suspect is the 12th person to be arrested since Scotland Yard's fresh investigation into phone hacking was launched in January.
These include a series of high-profile figures, including former News International chief executive Rebekah Brooks and ex-Downing Street communications chief Andy Coulson.
The scandal has already caused the closure of the News of the World after 168 years and the resignation of two top police officers, Metropolitan Police Commissioner Paul Stephenson and Assistant Commissioner John Yates.
A Scotland Yard spokesman said: "At approximately midday today a 61-year-old man was arrested by appointment at a London police station by officers from Operation Weeting and is currently in custody.
"He was arrested on suspicion of unlawful interception of communications ... It would be inappropriate to discuss any further details regarding these cases at this time."