Warren Little/Getty Images(LONDON) -- The scandal over Rupert Murdoch's News of the World tabloid has exploded across London, with Scotland Yard investigating the possibility that reporters and investigators for the paper hacked into the phones of victims of 7/7 -- the so-called London bus bombings of July 7, 2005, in which terrorists targeted the city's bus and subway systems and killed 52 people.



Outrage has spread since the original accusation that News of the World hacked the cell phone of Milly Dowler, a 13-year-old girl who disappeared in March 2002. Her remains were found southwest of London six months later, and a man was convicted this spring of killing her. Police are now trying to determine whether reporters not only listened to the teenager's voicemail, but deleted voicemail messages -- leading her parents to believe she was still alive and potentially obstructing the police investigation into her disappearance.



Scotland Yard has started to contact relatives of victims of the 2005 bus bombings, following up on allegations that a private detective working for News of the World obtained their cell phone numbers. It was unclear whether any of those phones had actually been hacked.



Police are checking other high-profile cases involving murder, abduction or attacks on children since 2001.



British Prime Minister David Cameron announced there will be two inquiries into the scandal: one looking at the behavior of the media, the other at the failure of the police.



Advertisers are now boycotting the News. Ford and Halifax Insurance have pulled ads; others, such as Virgin Media and the Tesco grocery chain said they are considering doing the same.



"It is absolutely disgusting what has taken place," Prime Minister Cameron said, speaking in the House of Commons before a hastily-called debate on the matter today. However, he said any inquiry into the News of the World would have to wait until the police investigation is concluded.



Pressure has grown on News of the World, a tabloid known for no-holds-barred coverage of celebrities and lurid crime stories. Its chief executive, Rebekah Brooks, was editor at the time of Millie Dowling's disappearance, and critics said she either must have approved of the hacking -- or had no control of her own paper.



The U.K., unlike the United States, has no First Amendment -- and a tradition of rough-and-tumble tabloid journalism. Glenn Mulcaire and Clive Goodman, two former News of the World employees, have previously served prison sentences for hacking into the phones of employees of the royal family.



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