CALIFORNIA, USA — BLOGGERS and activists from China, the Middle East and Latin America said Friday they were afraid that new Twitter policies could allow governments to censor messages, stifling free expression.

Thursday’s announcement that Twitter had refined its technology to censor messages on a country-by-country basis raised fears that the company’s commitment to free speech may be weakening. Twitter is trying to broaden its audience and make more money by expanding around the globe.

“I’m afraid it’s a slippery slope of censorship,” said social media commentator Jeff Jarvis, interviewed at a gathering of business and government leaders in Davos, Switzerland.

“I understand why Twitter is doing this. They want to be able to enter more countries and deal with the local laws. But, as Google learned in China, when you become the agent of the censor, there are problems,” he added.

Egyptian activist Mahmoud Salem, who tweets and blogs under the name “Sandmonkey”, questioned in a tweet whether Twitter “is selling us out”.

Twitter sees the censorship tool as a way to ensure individual messages, or tweets, remain available to as many people as possible while it navigates a gauntlet of different laws around the world.

Before, when Twitter erased a tweet it disappeared throughout the world. Now, a tweet containing content breaking a law in one country can be taken down there and still be seen elsewhere.

Twitter will post a censorship notice whenever a tweet is removed. That’s similar to what Internet search leader Google has been doing for years when a law in a country where its service operates requires a search result to be removed. Like Google, Twitter also plans to the share the removal requests it receives from governments, companies and individuals at the chillingeffects.org website.

The similarity to Google’s policy isn’t coincidental. Twitter’s general counsel is Alexander Macgillivray, who helped Google draw up its censorship policies while he was working at that company.

“One of our core values as a company is to defend and respect each user’s voice,” Twitter wrote in a blog post. “We try to keep content up wherever and whenever we can, and we will be transparent with users when we can’t. The tweets must continue to flow.”

Twitter, which is based in San Francisco, is tweaking its approach now that its nearly six-year-old service has established itself as one of the world’s most powerful megaphones. Daisy chains of tweets already have played instrumental roles in political protests throughout the world, including the Occupy Wall Street movement in the United States and the Arab Spring uprisings in Egypt, Bahrain, Tunisia and Syria.

It’s a role that Twitter has embraced, but the company came up with the new filtering technology in recognition that it will likely be forced to censor more tweets as it pursues an ambitious agenda. Among other things, Twitter wants to expand its audience from about 100 million active users now to more than one billion.

Reaching that goal will require expanding into more countries, which will mean Twitter will be more likely to have to submit to laws that run counter to the free-expression protections guaranteed under the First Amendment in the US.

If Twitter defies a law in a country where it has employees, those people could be arrested. That’s one reason Twitter is unlikely to try to enter China, where its service is currently blocked. Google for several years agreed to censor its search results in China to gain better access to the country’s vast population, but stopped that practice two years after engaging in a high-profile showdown with Chain’s government. Google now routes its Chinese search results through Hong Kong, where the censorship rules are less restrictive.

In China, where activists quickly caught on to Twitter despite it being blocked inside the country, artist and activist Ai Weiwei tweeted Friday: “If Twitter censors, I’ll stop tweeting.”