The counter-claim, filed in a San Francisco federal court yesterday, comes weeks after Yahoo sued Facebook for patent infringement.
Ted Ullyot, Facebook's general counsel, said in a statement: "From the outset, we said we would defend ourselves vigorously against Yahoo's lawsuit, and today we filed our answer as well as counter-claims against Yahoo for infringing ten of Facebook's patents.
"While we are asserting patent claims of our own, we do so in response to Yahoo's short-sighted decision to attack one of its partners and prioritize litigation over innovation."
Following Yahoo's legal action last month, Facebook purchased a package of patents from IBM, to bolster its defences in the patent wars.
Facebook reportedly bought 750 patents, covering various technologies, to significantly boost its portfolio, which at the time stood at 56 patents.
The two companies have worked together in the past, for example on Yahoo’s Facebook app.
In a recent , Robert Bridge, director and head of marketing for Yahoo EMEA, talked up this relationship, prior to the news hitting the headlines.
When Yahoo sued Facebook, it brought the ongoing patent wars into the domain of social media for the first time.
It was the first major move by the newly installed Yahoo chief executive Scott Thomspson. According to AllThingD, the company is expected to announce a major restructure in the next few days, which could results in thousands of job cuts.
Yahoo did not respond to request for comment at the time of publishing.
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