Adobe and Yahoo have announced a programme which will place adverts in PDF files.

The scheme will allow website owners to run text-based ads from Yahoo's advertising network within the PDF documents.

To run the ads, site owners submit the PDF files to the service, which embeds the advertisement in the file. The ads are then placed in a separate panel adjacent to the original PDF content.

The service will not require users to download any additional software or plug-in, but will only display ads when viewed through Adobe's Acrobat or Reader applications.

Every time a user opens the file, a new ad is displayed from the Yahoo network.

Yahoo will also offer a tracking service to allow site owners to monitor the performance of the PDF ads.

The aim is to give publishers the opportunity to make ad revenue from a format traditionally considered 'free' in comparison to HTML files.

Todd Teresi, senior vice president of Yahoo Publisher Network, called the programme "a natural step forward" for Yahoo's ad business.

"This partnership with Adobe creates a previously untapped opportunity for advertisers to connect with qualified audiences while opening new revenue streams for publishers," he said.

The service is currently listed as a beta and is limited to English language publishers in the US.