The service will allow publishers to make money by including adverts linked to the content of a PDF document in a panel at the side of the page.

According to the BBC News website, the move is Yahoo's latest way of expanding the places it can advertise online, and follows deals with auction site Ebay and cable TV group Comcast.

The advertisements will not, however, appear if the document is printed.

The so-called dynamic adverts will be changed for specific audiences and will be rotated to ensure users never see the same advert twice.