A journalist was arrested on Wednesday on suspicion of computer hacking.
The 28-year-old man, understood to be the former Times journalist Patrick Foster, was held at his north London home on Wednesday morning.
It is understood the arrest relates to a Scotland Yard investigation into the hacking of the email account of Lancashire detective Richard Horton in 2009 which unmasked him as the author of the anonymous NightJack blog.
Foster is 11th person to be arrested by detectives from Operation Tuleta, the Metropolitan Police investigation of breaches of privacy, which is running alongside the phone-hacking scandal investigation, Operation Weeting.
He was also arrested on suspicion of conspiracy to pervert the course of justice.
A Scotland Yard spokesman said: "Officers from Operation Tuleta, the investigation into criminal breaches of privacy including computer hacking which is being carried out in conjunction with MPS phone hacking inquiries, arrested a man in North London this morning, 29 August.
"The 28-year-old man, a journalist, was arrested at his home address at approximately 7am for suspected offences under the Computer Misuse Act 1990 and suspected conspiracy to pervert the course of justice, contrary to the Criminal Law Act 1977."
He was being questioned at a North London police station.