Google said Monday the Chinese government is interfering with its email services in China, making it difficult for users to gain access to its Gmail program.
Google Inc. said its engineers have determined there are no technical problems with the email service or its main website.
"There is no technical issue on our side; we have checked extensively. This is a government blockage carefully designed to look like the problem is with Gmail," the company said in a brief statement.
China has some of the world's strictest Internet controls and blocks many popular social media sites, including Youtube, Facebook and Twitter. The government has intensified those efforts after pro-democracy protest erupted across the Middle East in January.
Around that time, anonymous calls for protesters to gather for a "Jasmine Revolution" in China triggered a crackdown by Chinese authorities, who stepped up Web censorship and deployed huge numbers of police to planned protest sites. No protests happened.
A Google spokesperson said users in China have reported having intermittent problems with the service since the end of January.
Problems include difficulty accessing the home page for Gmail and problems sending emails when logged into the service. The instant messaging function is often not working as well.
Google officials said the blocking appears to be more sophisticated than other problems experienced by users in the past because the disruption is not a complete block.
A company spokesperson refused to say if Google has raised the issue directly with Chinese government officials.
Google has had highly public run-ins with the Chinese government.
In January last year, Google announced that it would no longer cooperate with the government's requirement to censor search results for banned sites. It also complained about major attacks on its website by Chinese hackers, suggesting the government may have been instigated the attacks.
Google moved its Chinese-language search engine to Hong Kong, which operates under separate rules from the rest of mainland China.