Yandex on Tuesday announced that it is adding public Facebook data to the index of data mined for queries handled by the Russian Internet search giant.

"As of today, public content from Facebook users in Russia, Ukraine, Belarus, Kazakhstan, other CIS countries and Turkey will be available for indexing by Yandex as soon as it has been published," Russia's biggest search engine said in an English-language statement.

Yandex said that an agreement with Facebook gives it full access to the California-based social network's "firehose" of public data.

"Users can find out what those on the social network are saying about the current headline news events, for example, or the latest movies," Yandex said.

"In the near future, Yandex's search results will display not only Facebook users' posts but also others' comments on them."

Facebook profiles or posts set to "private" by users will not be searchable.

Microsoft also has a deal with Facebook to incorporate public social network information into search results at Bing. Google has no formal agreement with Facebook for its data stream but can in many cases find public posts on the social network.

"Information about the hot topics in social networks is an important factor for a search engine in answering users' questions," Yandex said in a blog post.

"The intensity of discussion on any subject in social media is proof of the topic's relevance."

"Yandex's search results will incorporate articles and videos that have had particular resonance on the social network," the Russian search engine said.

"The popularity of materials on Facebook will be taken into consideration when ranking search results."

Facebook did not reply to an AFP inquiry about the alliance, which reportedly involved no money changing hands.

Yandex raised some $1.3 billion in a 2011 public offering on the Nasdaq. It handles some 60 percent of search queries in Russia and has a presence in several other countries.