A top microblog in China has blocked searches for the Chinese words for "Hillary Clinton" and "Hillary", just a day after the U.S. Secretary of State gave a speech urging governments to end Internet censorship. China's Sina microblog, a Twitter-like service, appeared to be blocking the terms on Thursday morning. "In accordance with the relevant laws, regulations and policies, the search result did not display," said the response on the microblogging site. In China, government censors routinely force local websites to remove politically sensitive content. Clinton had given a speech earlier this week, saying countries such as China would face long-term economic and social costs that would lead to civil unrest if their censorship of the Internet continued. The U.S. Embassy in Beijing tried to start discussions about the speech using Chinese microblogs. But it appears that the posts were quickly taken down by Chinese government censors. The embassy referred to a statement made by U.S. Ambassador to China Jon Huntsman that said, "We are disappointed that some Chinese Internet sites have decided to remove discussion of Secretary Clinton's Internet freedom speech from their websites. It is ironic that the Chinese are blocking an online discussion about Internet freedom."In response to Clinton's speech, China said the "Internet is open" in the country and it supports its development. "But we are against any other country using Internet freedom as a pretext to interfere in other countries' affairs," China Foreign Ministry spokesman Ma Zhaoxu said on Thursday. The Hillary-censoring comes just weeks after Sina and other microblogs in China also began censoring searches for the Chinese word "Egypt" following the anti-government protests in the Middle Eastern country. China has been restrictive on news and information released on the politically sensitive topic, in order to prevent the same kind of civil unrest from occurring in the country, said Phelim Kine, an Asia researcher for New York-based Human Rights Watch."They are working diligently to ensure new types of technology are neutered and controlled," Kine said. "The Chinese government is gambling by keeping a tight lid on control and keeping a facade of harmony, believing that this will translate and continue it's long-term control."China currently has the world's largest Internet population, at 457 million users. But the country has invested heavily in censoring the Web for politically sensitive content and at times even blocking entire sites. Facebook and Twitter were both blocked by the Chinese government in 2009 after ethnic riots broke out in China's western Xinjiang region. The sites remain blocked.In November, Sina reported that it's microblogging service had more than 50 million users. The user base is expected to reach 100 million users in the first half of 2011.Sina did not immediately respond to requests for comment.