Yahoo is threatening action unless Facebook licenses some of its technologies, as other web and technology companies are said to have done.
The move by Yahoo puts it in conflict with Facebook with which the company has a beneficial relationship, particularly in the area of integration of Yahoo News with Facebook.
Traffic to the mobile Yahoo News web app from Facebook Mobile has increased three-and-a-half times since 14 February to 1.6 million visitors a day, according to a post last week on Facebook's developer blog.
Yahoo said: "Yahoo! has a responsibility to its shareholders, employees and other stakeholders to protect its intellectual property. We have invested substantial resources into these innovations. Recognising that, other major web and technology companies have already licensed some of these technologies. We must insist that Facebook either enter into a licensing agreement or we will be compelled to move forward unilaterally to protect our rights."
Yahoo's demand is the latest in intellectual property disputes in the US which have so far embroiled top technology companies like Google, Oracle, Motorola Mobility and Apple.
Yahoo did not disclose which were the technologies it wanted Facebook to license. The New York Times said in a report that Yahoo is seeking to force Facebook into licensing 10 to 20 patents over technologies that include advertising, personalisation of Web sites, social networking, and messaging, citing people briefed on the matter.
A Facebook spokesman said the company hadn't had the opportunity to fully evaluate the claims.
Once a leading Internet company, Yahoo now finds itself trailing behind newer entrants like Google and Facebook. The company recently witnessed the exit of key people including co-founder Jerry Yang, and chairman Roy Bostock who said in February that he would not stand for re-election, amidst unconfirmed reports that company may be up for sale.
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