Twitter, a tool of choice for dissidents and activists around the world, found itself the target of global outrage Friday after unveiling plans to allow country-specific censorship of tweets that might break local laws.

It was a stunning reversal for a company that prides itself in promoting unfettered expression. Twitter insisted its commitment to free speech remains firm and sought to explain the nuances of its policy, while critics — in a barrage of tweets — proposed a boycott and demanded that the censorship initiative be scrapped.

"This is very bad news," tweeted Egyptian activist Mahmoud Salem. Later, he wrote, "Is it safe to say that (hash)Twitter is selling us out?"

In China, where activists have embraced Twitter even though it's blocked inside the country, artist and activist Ai Weiwei tweeted: "If Twitter censors, I'll stop tweeting."

San Francisco-based Twitter, founded in 2006, depicted the new system as a step forward. Previously, when Twitter erased a tweet, it vanished throughout the world. Under the new policy, a tweet breaking a law in one country can be taken down there and still be seen elsewhere.

Twitter said it will post a notice whenever a tweet is removed and will post the removal requests it receives at the website chillingeffects.org.

The critics are jumping to the wrong conclusions, said Alexander Macgilliviray, Twitter's general counsel.

"This is a good thing for freedom of expression, transparency and accountability," he said. "This launch is about us keeping content up whenever we can and to be extremely transparent with the world when we don't. I would hope people realize our philosophy hasn't changed."