Facebook on Tuesday filed a countersuit against Yahoo, arguing that Yahoo is infringing on 10 Facebook-owned patents.

Facebook said that several major Yahoo products infringe upon its patents - from the Yahoo homepage and Flickr to Yahoo Sports and Yahoo News.

The suit comes almost a month after Yahoo filed suit against Facebook over patents related to its ad network, privacy, customization, messaging, and social networking as a whole. Facebook has denied any wrongdoing and called Yahoo's suit "puzzling."

In its countersuit, Facebook cites patents related to its newsfeed, photo tagging, user recommendations, social-networking profiles, and more.

Yahoo is accused of infringing on Facebook's newsfeed patent - described as "generating a feed of stories personalized for members of a social network" - via the photostream, recent activity, and group activity options on Flickr. Facebook argued that Flickr is also in violation of its tagging patent with "People in Photos" option on Flickr.

Various Yahoo homepages, meanwhile, violate Facebook's patent for a "headline posting algorithm," Facebook argued. According to an abstract of the patent, the technology "uses the topic interest flags to determine which articles and other customizable elements of the database are shown on a particular member's home page."

The remaining patents all have customization aspects that are infringed upon via various Yahoo products, Facebook said.

Facebook is asking the court to dismiss Yahoo's case, rule in favor of Facebook on its own complaints, and award damages and costs.

In an e-mailed statement, Yahoo said, "We have only just received Facebook's answer and counterclaims, but on their face we believe they are without merit and nothing more than a cynical attempt to distract from the weakness of its defense."

"As we have made clear from the outset, the unauthorized use of our patented technology is unacceptable and must be resolved appropriately," Yahoo continued. "Other leading companies license these technologies, and Facebook must do the same or change the way it operates. We have proposed that Facebook join us in discussions to resolve the matter, but our overtures have been rejected. As a result, we are prepared to continue to seek redress through the courts."

Yahoo and Facebook have worked together for a number of years. Back in December, Yahoo expanded its Facebook social sharing feature to 26 more Yahoo sites around the world, meaning there were more options to automatically share the Yahoo stories you're reading with Facebook friends.