London ( CNN ) -- Singer Charlotte Church on Monday blasted the News of the World tabloid for its decision to publish a lurid story about her father having an affair while her mother was getting treatment for mental illness . `` They knew how vulnerable she was and still printed a story like that , which is just horrific , '' she said . The former child star also spoke of her anger at finding out her phone may have been hacked by a private investigator working for the Rupert Murdoch tabloid . The investigator , Glenn Mulcaire , had details of her phone and those of her parents , friends and former boyfriends , Church said police had told her . She was testifying before a wide-ranging British government-backed inquiry into press ethics and practices in the country . Sparked by the revelation that News of the World tabloid hacked into the voice mail of a murdered 13-year-old girl in search of stories , the Leveson Inquiry has been hearing from high-profile figures for more than a week . Church described how upset she was at the leak of the news of her daughter 's birth , the rifts it caused with her family and friends when she accused them of revealing the details , and her later guilt at realizing the source was probably hacking , not leaks from those close to her . And she said falsehoods published in the press were particularly damaging because readers believe there are rules to prevent that from happening , `` So if they see it in print , it must be true -- and that 's not the case . '' Former Tony Blair spokesman Alastair Campbell is due to testify later this week , but a written copy of his opening statement appears to have leaked online . Paul Staines , who blogs as Guido Fawkes , posted what he said was a copy of Campbell 's testimony in which he speculates about the possibility that the Daily Mirror found out though phone hacking that Tony Blair 's wife was pregnant . `` I think it is at least possible that this is how the stories got out , '' Campbell says in the statement published by Staines . Campbell said on Twitter Sunday he was `` genuinely shocked someone has seen fit to leak my statement to Leveson . '' The Daily Mirror is not a Murdoch paper . Piers Morgan was editor of the paper at the time of Cherie Blair 's pregnancy , and he now hosts the show `` Piers Morgan Tonight '' on CNN . Morgan , who has vigorously denied ordering phone hacking , is due to testify before the Leveson Inquiry at a later date yet to be determined . Celebrities who have already testified before the inquiry include `` Harry Potter '' author J.K. Rowling and `` G.I . Joe '' actress Sienna Miller , who both complained of being hounded by paparazzi . Actor Hugh Grant also appeared before the panel , and he implied that police leaked information to the tabloid press . He also accused the Mail on Sunday of hacking . Police investigating phone hacking by journalists say that about 5,800 people , including celebrities , crime victims , politicians and members of the royal family , were targets of the practice by journalists in search of stories . It involves illegally eavesdropping on voice mail by entering a PIN to access messages remotely .
NEW : I believe to prevent falsehoods from being printed , Charlotte Church says . Charlotte Church says a private investigator had her phone details . Former Tony Blair spokesman Alastair Campbell is due to appear later this week . Police say 5,800 people were suspicious of journalists looking for stories .