Yahoo asked Facebook to license technologies covered by its intellectual property and threatened to take legal action if the companies don't reach an agreement, according to The Washington Post.
In news first reported by the New York Times, Sunnyvale-based Yahoo! said it would sue if Facebook doesn't work out a licensing agreement, as some other companies have done.
The dispute covers between 10 and 20 patents, the Times said.
Yahoo didn't say what other companies are paying licenses for its technology.
Facebook, a rich, popular business getting ready for what could be a gargantuan IPO this spring, is a tempting target for lawsuits of many types, including patent suits.
"We must insist that Facebook either enter into a licensing agreement or we will be compelled to move forward unilaterally to protect our rights," Sunnyvale, Calif.-based Yahoo said in a statement.
In ohter legal news, Reuters reported on Tuesday, February 28, that complaints from Microsoft and other companies may prompt the European Union to broaden its ongoing investigation into Google. Microsoft reportedly has complained to the EU about Google's social-networking platform, Google+, but the Redmond software company says the report isn't true.
"We have not filed a complaint regarding Google+," MJ Foley quoted a Microsoft spokesperson as saying.
The Reuters report citing two people "familiar with the matter." It said neither the companies nor European Commission officials would discuss the complaints against Google+, which launched in June:
"Microsoft and the other companies expressed their concerns informally, the people said, declining to provide details about the nature of the complaint about Google+ because of the sensitivity of the matter."