The hopes of Sally Dowler, the mother of murdered schoolgirl Milly Dowler, were wrongly raised after a private detective erased messages on her daughter's phone, the Leveson Inquiry has heard.

Sally was ecstatic when she heard her daughter's voice mail and thought she might be safe.

But the inquiry was told that News of the World investigator Glenn Mulcaire had hacked Milly's mobile phone and deleted all the messages to create space for others. The Dowler family believe that their phones were also hacked after Milly was abducted in 2002, the Mirror has reported.

According to the newspaper, David Sherborne, who is representing the Dowler family and 48 other alleged victims of the News of the World's snooping, described Mulciare "cruel" and "insensitive".

"Mulcaire, acting in the course of his work for the newspaper, had deliberately accessed and listened to the missing 13-year-old's voicemail. Dowler's family will tell you in their own words what it felt like in those moments when Sally finally got through to her daughter's voicemail after persistent attempts had failed because the box was full, and the euphoria which this belief created, false as it was unfortunately. There are no words which can adequately describe how despicable this act was," Sherborne was quoted by the Mirror as saying.

Mulcaire, along with former News of the World royal editor Clive Goodman, was jailed for intercepting voicemails left on phones of royal supporters in 2007.

The others who were allegedly targeted by the News of the World included Sara Payne, whose 8-year-old daughter Sarah was killed by paedophile Roy Whiting in Sussex in 2000.

Payne had worked with News of World to campaign for a strong child protection laws.

Meanwhile, Guardian editor Alan Rusbridger told the inquiry: "We are sure you will have in your mind the good things that journalists do, which, more than ever, need protection, as well as the work of the 99 per cent of British journalists who wouldn't have a clue how to hack a phone and who don't snoop into the private lives of others."