Ms. Akers said Mr. Murdoch’s papers had obtained information from two stolen cellphones. One disappeared in Manchester, in northern England, and the other in southwest London. She said one of the phones appeared to have “been examined with a view to breaking its security code,” to gain access to its contents — presumably other phone numbers and perhaps e-mails, text messages and calendars. The authorities are trying to establish whether the thefts were isolated incidents or “the tip of the iceberg,” she said.

It was not clear whether the phones might have been stolen at the behest of tabloid reporters, or were passed on to them by others who found or stole the phones.

Officers are examining 101 allegations of data interception, Ms. Akers said, in an inquiry that has yielded seven arrests.

Another inquiry, into bribes paid to public officials, has led to 41 people being arrested — including 23 current and former journalists, four police officers, nine current and former public officials and others described as conduits for the bribes, Ms. Akers said. One prison official is accused of having received nearly $55,000 from Mr. Murdoch’s newspapers and from the rival Trinity Mirror and Express newspaper groups from April 2010 to June 2011, for information that Ms. Akers did not describe.

She said the initial investigation into phone hacking led to the arrest of 15 current and former journalists, 11 of whom will return to police stations on Tuesday as part of their bail conditions. The police have notified 2,615 people that they may have been targets, and 702 — many of them celebrities, politicians and sports stars — “are likely to have been victims” of actual voice mail interceptions, she said.