A man has been arrested by officers investigating phone hacking, Scotland Yard said.
The 60-year-old was arrested at his home in south west London. He was held on suspicion of conspiring to intercept communications and is being questioned at a south London police station.
So far 25 people have been arrested in connection with Operation Weeting, the investigation into phone-hacking.
A Scotland Yard spokesman said: "Officers from Operation Weeting, the Metropolitan Police Service inquiry into the hacking of telephone voicemail boxes, arrested a man in south west London this morning, Thursday August 30.
"The 60-year-old man was arrested at his home address at approximately 6.45am on suspicion of conspiring to intercept communications contrary to Section 1 of the Criminal Law Act 1977. He is being interviewed at a south London police station."
The Met refused to comment on whether or not the suspect was a journalist.
Former News International chief executive Rebekah Brooks will appear at Westminster Magistrates' Court on Monday charged over the Weeting investigation.
Seven other people including David Cameron's former spin doctor Andy Coulson appeared at the same court earlier this month over hacking charges. The group contained six members of staff from the now-defunct tabloid the News of the World (NOTW).
Former NOTW editor Coulson is accused, along with ex-managing editor Stuart Kuttner, former news editor Greg Miskiw, former head of news Ian Edmondson, ex-chief reporter Neville Thurlbeck and former reporter James Weatherup. Private investigator Glenn Mulcaire has also been charged.
Brooks and Coulson face specific charges of conspiring with others to illegally access the voicemail of murdered schoolgirl Milly Dowler.