The first person to be arrested in connection with claims of computer hacking by private investigators working for News International was released on bail tonight.
The 52-year-old man was detained earlier today under the Met Police's Operation Tuleta, which runs alongside the Operation Weeting probe into phone-hacking.
The suspect, who was arrested in Milton Keynes on suspicion of Computer Misuse Act offences, was later bailed to return to a London police station in early December, police said.
A police spokesman said: "Operation Tuleta is investigating a number of allegations regarding breach of privacy, received by the Metropolitan Police Service (MPS) since January 2011, which fell outside the remit of Operation Weeting, including computer hacking."
Tuleta was launched over the summer after a "scoping exercise" into allegations surrounding the use of private detectives.
Officers working on the inquiry have been reporting to Deputy Assistant Commissioner Sue Akers, who heads the inquiry into mobile phone interceptions at the now defunct News of the World.
Scotland Yard's phone-hacking squad is working its way through 300 million emails from News International.
Commissioner Bernard Hogan-Howe says police have already spent up to £3 million on salaries, with officers speaking to 1,800 of 6,000 potential victims.
A total of 120 officers and staff are now working on the entire investigation after 1,800 people came forward to express fears that they may have been hacked.
Jamie Pyatt, 48, became the first Sun journalist to be arrested earlier this month as part of Operation Elveden, an investigation into illegal payments to police.
Other suspects include former News International chief executive Rebekah Brooks, ex-Downing Street communications chief Andy Coulson and the Sunday tabloid's former royal editor Clive Goodman.
Mrs Brooks and Mr Coulson are both former editors of the News of the World, which was closed in July at the height of the hacking scandal following revelations that murdered teenager Milly Dowler's phone was involved.