Sara Payne's details held by NOTW investigator

(PA)

The phone-hacking scandal took a sinister new twist last night after it emerged that police have warned the mother of Sarah Payne that a phone given to her by the News of the World may have been targeted by a detective working for the paper.

Sara Payne was given the phone shortly after her eight-year-old daughter Sarah was abducted and murdered in July 2000.

Police had previously told her that her name was not among those recorded by the News of the World investigator Glenn Mulcaire, but on Tuesday officers from Operation Weeting said they had found her personal details among the investigator's notes. They had previously been thought to refer to a different target.

Friends of Ms Payne said she was "absolutely devastated and deeply disappointed" at the disclosure. Her campaign to give parents access to the criminal records of potential partners was championed by the News of the World, in particular by its former editor, Rebekah Brooks.

Ms Payne even wrote a farewell column for the paper's final edition, referring to its staff as "my good and trusted friends".

Last night Ms Brooks put out a statement saying it was "unthinkable" that anyone on the newspaper knew that Sara or others campaigning for "Sarah's Law" – the right for parents to know if a convicted child sex offender was living in their area – had been phone-hacked.

"It is imperative for Sara and the other victims of crime that these allegations are investigated and those culpable brought to justice," said Ms Brooks.

The Labour MP Chris Bryant, himself a victim of phone hacking, accused Ms Brooks of "utter hypocrisy". He said he was reminded of the quote from Hamlet that "one may smile and smile and be a villain". The Labour MP Tom Watson said it was a "betrayal of trust".

"I think we need to know when Rebekah Brooks knew about this, and having read the statement I notice that she doesn't give a categorical denial, so I'd like to hear a bit more from Ms Brooks about what she knew," he said.

Earlier this month, when it emerged that a phone belonging to the murdered teenager Milly Dowler had been hacked, rumours circulated among journalists that Sara Payne might also have been a victim.

The News of the World's sister paper, The Sun, reported on its website that Ms Payne had been told there was no evidence to support the rumours.