The man, in custody at a north London police station, was detained on suspicion of conspiring to intercept voice-mail messages, Metropolitan Police said in a statement. He is the 16th person arrested since a renewed probe of the newspaper began in January. The Guardian separately said its reporter Amelia Hill, who has written extensively about the case, was questioned recently by police investigating leaks from inside the force.

“Journalists would no doubt be concerned if the police sought to criminalize conversations between off-record sources and reporters,” the Guardian said in an e-mailed statement.

The police investigation, and revelations by the Guardian that the News of the World hacked the voice mail of a murdered school girl, led to News Corp.’s decision to close the tabloid and scrap a planned bid for British Sky Broadcasting Group Plc. Authorities are also probing whether police officers were paid for news and whether journalists hacked computers for stories.

A London police detective investigating the hacking was arrested last month over claims he leaked information about the case to the media. U.K. newspapers have on several occasions published details of phone-hacking arrests before public announcements were made.

Murder Victim

The 190-year-old Guardian took down the News of the World, Britain’s best-selling Sunday newspaper, by exposing that the Rupert Murdoch-owned tabloid hacked the voice mail of murder victim Milly Dowler.

Four former executives at News Corp.’s U.K. unit testified yesterday before Parliament, including two men who challenged testimony given to lawmakers in July by James Murdoch, the company’s deputy chief operating officer, about details surrounding his knowledge of the scandal.

A spokesperson for New York-based News Corp.’s U.K. unit declined to comment.

Previous arrests include former editors and journalists who worked at the newspaper when private detective Glenn Mulcaire was paid to hack into celebrities’ voice mails. Former News of the World editors Rebekah Brooks and Andy Coulson and former managing editor Stuart Kuttner are among those that have been questioned by police this year.