Paedophiles should not be able to escape prosecution by simply wiping child porn images from their computer hard drives, campaigners said last night.
The law should be changed to allow the prosecution of perverts who use so-called "evidence erasing" software, the Children's Charities Coalition for Internet Safety (CHIS) urged.
Computer magazines which distribute the programmes as front-cover give-aways were also criticised for encouraging people to break the law.
In a letter to the Home Office, CHIS executive secretary John Carr said: "We think it is irresponsible of the computer magazines ... to promote and advertise software of this kind in the way that they do. The purpose of these programmes is not disguised in any way," said Mr Carr, an internet safety expert from children's charity NCH.
"Quite simply they do multiple wipes of all or part of a computer hard drive.
"This 'eliminates' any 'evidence' of anything and everything that has been performed on that computer that the owner does not want anyone else to see. If the computer has been used in the commission of a crime, for practical purposes it makes it impossible for law enforcement to recover anything of value that could be produced in a court."
CHIS brings together charities including the NSPCC, NCH, Barnardo's and Childline to combat child porn on the Web.