Sara Payne, mother of murdered seven-year-old Sarah Payne, has complained that the Daily Mirror quoted her backing its campaign to jail for life paedophiles who commit a second serious sex attack without speaking to her.
Both the Daily Mirror and The Sun are involved in high-profile campaigns backing longer jail sentences for paedophiles.
The Mirror's campaign began on Tuesday, a day after The Sun began its "Judges on trail" campaign, aimed at sacking judges who handed down "soft" sentences.
The Mirror stated: "Sarah's mum backs our paedo law campaign" on its front page on Tuesday with a picture of Sara Payne and quoted her extensively on inside pages.
But Payne, who has campaigned with the News of the World for a public sex offenders' register, told Press Gazette: "I am extremely disappointed that I have been misrepresented in Tuesday's Daily Mirror. I generally support all anti-paedophile campaigns and applaud everyone who works hard to make this country a safer place for her kids.
"However, it is wrong to picture me on the front page of a national newspaper with a headline and direct quotes when nobody has actually bothered to call me.
"This is sloppy journalism at its very worst. I have a very good relationship with the media after years of campaigning for Sarah's Law and would have happily given them some quotes, but the fact is that I had not spoken to the Daily Mirror for months until yesterday when someone from the newspaper phoned me to apologise. I have written to the editor of the Daily Mirror to make my views on this clear."
A Mirror spokesman said: "The Mirror refutes any suggestion that Sara Payne's quotes were not genuine or were obtained through subterfuge of some kind. Sara is very supportive of our campaign and stands by her quotes.
"The idea that her comments were made up is entirely wrong and completely without basis. We suspect this is a case of another media organisation making mischief after having been scooped once again by the Daily Mirror."