(AP) -- Facebook CEO Mark Zuckerberg toured the offices of China's top search engine Monday during a visit that has sparked speculation the social networking magnate is looking for business opportunities in the world's largest Internet market.
Facebook is blocked on the mainland, but Zuckerberg has expressed a business interest in China and has studied Mandarin.
Photos of Zuckerberg's visit to Baidu Inc. were quickly posted online.
Kaiser Kuo, Baidu's director of international communications, told The Associated Press that Zuckerberg had lunch with Baidu CEO Robin Li. He said he didn't know what they talked about but added that the two had met before.
Zuckerberg, who co-founded Facebook, is traveling with his girlfriend, Priscilla Chan, and no apparent entourage.
"Mark has had a long personal interest in China," Kuo said.
But Zuckerberg has also hinted that he's interested in more than that, saying during a speaking engagement in October, "How can you connect the whole world if you leave out 1.6 billion people?"
Kuo tried to tamp down such speculation, though, posting on his Twitter account: "C'mon people. Robin and Mark have known each other for a while. Mark's interest in China is well known. Keep the speculation in check."
Not many in China are familiar with Facebook, but Zuckerberg is known for being Time magazine's 2010 Person of the Year, according to Kuo.
Aside from a visit Monday morning to a Tibetan temple in Beijing, the rest of Zuckerberg's schedule in China is not known.
China censors Internet content it deems politically sensitive and blocks many websites, including Facebook, Twitter and YouTube.
China's nervousness about the power of social networking was on display Monday, when the computer scientist seen as the father of China's "Great Firewall" of Internet controls apparently was forced offline by angry comments within a few hours of opening a microblog.
Anonymous posters peppered the microblog of Fang Binxing with hundreds of caustic or sarcastic comments, and eventually all of Fang's posts and the responses were taken down.
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