On Thursday, Russian search company Yandex launched a new social search app for the iPhone, called Wonder. The app relied on Facebook, Twitter, Instagram, Foursquare, iTunes and Last.fm data. Unfortunately for Yandex, Facebook pulled access to its data, which was kind of a key feature.

In fact, Facebook has been putting the kibosh on a number of apps it sees as potential competitors when it comes to API access, as Josh Constine at TechCrunch reports, citing Twitter’s new Vine video app and Voxer as other casualties, as both were cut off from Facebook’s Find Friends API, which lets apps give users access to their Facebook friends.

Facebook’s Platform policy says, “Competing social networks: (a) You may not use Facebook Platform to export user data into a competing social network without our permission; (b) Apps on Facebook may not integrate, link to, promote, distribute, or redirect to any app on any other competing social network.”

It also says, “You must not include data obtained from us in any search engine or directory without our written permission.” Constine shares a statement it receive from Yandex before Facebook even blocked its access:

We note that Yandex is not in violation of Facebook Platform Policies providing for restriction to use data obtained from Facebook in a search engine or directory for the reason that Wonder is not a search engine or a directory. Our application is a personal assistant that helps browse and organize information that is exclusively available to and associated with relevant account of the relevant user in various social networks and services.

On the contrary, [a] search engine is conventionally understood as an information location tool which automatically indexes tens of thousands of publicly available websites, fetches information with unrestricted access and is freely accessible to any Internet user. In addition, we would like to note that Wonder requests [a] user for specific permission to access each portion of information available to the user through a social network or services and never accesses information or data which is beyond the consent, availability for or extent of permission expressly granted by the application user. It is further to be noted, that the application does not perform any automated operations, unless these are specifically permitted by the user.

Clearly, Yandex saw this as a potential problem, and launched anyway, but based on the nature of the app, and how it is coinciding with the roll-out of Facebook’s own Graph Search, it’s no surprise that Facebook would view it as a competitor.

The companies are reportedly in talks about how to proceed with the app, but if Facebook doesn’t budge, it’s not going to make Wonder nearly as attractive to users as it may have been otherwise (and the jury was still out on that anyway). Apparently, Wonder can still operate with the other aforementioned networks’ data (for now), and that even includes Facebook’s Instagram. The real social data, as we all know, however, is in Facebook itself.