Churnalism.com, launched by charity the Media Standards Trust, enables the public to compare releases with more than three million articles from the national newspaper press, BBC or Sky from the last three years.
According to a release, the site was inspired by Nick Davies' book Flat Earth News in which he discusses the issue of 'churnalism', claiming that PR material appears in 54 per cent of news stories.
On the new site, in cases where more than 20 per cent of an article and press release overlap, the new search engine will highlight it as a potential example of 'churn'. The results of a search then offer statistics on how much has been cut, pasted and how many characters overlap.
The system itself currently works by automatically scraping some sites for press releases and the rest are crowd-sourced. According to a blog post by the director of the Media Standards Trust, Martin Moore, the automatically scraped press releases will be from organisations such as big retailers, the government and some police forces, known to regularly send out releases. Examples will also be highlighted via a new Twitter account.
As the site develops Moore said he hopes to link churnalism.com with the MST's journalisted.com site, a database of journalists, enabling the services to flag up offending journalists.
"News organisations can now be much more transparent about the sources of their articles, but most of them still aren't," Moore added in the release.
"Hiding the connection between PR and news is not in the interests of the public. Hopefully churnalism.com will nudge them to be more open about their use of PR material.
"Even with press releases that are clearly in the public interest - medical breakthroughs, government announcements, school closures, and perhaps even this website launch - it is still better that articles are transparent about their sources."