Google has started to encrypt searches made by people in China.
The move is widely seen as a way for users of the search engine to avoid official scrutiny of where they go online, reports the Washington Post.
It is also seen as a reaction to continuing revelations about the extent of surveillance of web browsing habits by the National Security Agency (NSA) .
Google said it was now encrypting all the text involved in searches "by default" around the world.
Users in other countries, such as the US and UK, have had the option to encrypt searches since 2010.
"The revelations of this past summer underscored our need to strengthen our networks," said Google spokeswoman Nikki Christoff in a statement.
Documents taken by whistleblower Edward Snowden have shown that the NSA has had regular access to the data centres operated by Google and many other web firms.
In China, the web browsing and social media habits of citizens are monitored by a very sophisticated system that attempts to stop people finding out about or sharing information on sensitive subjects.
Ms Christoff said encrypting search text was just one of many improvements it had made in the past few months to help people maintain their privacy.
Google reduced its presence in China in 2010 after it clashed with the nation's authorities over demands to censor searches or redirect people to government-approved sites. This has meant that Google has a very small share of all searches, about 5%, carried out in China,
Most Chinese people tend to use the home-grown Baidu search engine that does comply with official censorship requests.
In Europe, Google has come under fire for not doing enough to protect users' privacy. In January EU Justice Commissioner Viviane Reding said firms should face hefty fines if they abused personal data. She said fines handed down to Google over data breaches were "pocket money".