New online speech restrictions are taking effect Friday in Russia, making it more difficult for bloggers to remain anonymous and requiring social-networking sites like Facebook to retain user data for at least six months.

Under a measure approved by Russia's parliament in April, the law also demands that the social media data be stored within the country's boundaries so it can be available for government inspection.

Human Rights Watch called the development "another milestone in Russia's relentless crackdown on free expression," in a statement given to the BBC. The Internet, the group added, "is the last island of free expression in Russia and these draconian regulations are clearly aimed at putting it under government control."

The new regulations also say that bloggers with at least 3,000 daily readers must register with Roskomnadzor, the regulator that also oversees Russia's main media outlets. Russia has been cracking down on Internet freedoms under President Vladimir Putin, who has decried the Internet as a "CIA project."

The latest law follows regulations adopted two years ago giving the government powers to disable websites without due process. Last month, for example, Roskomnadzor demanded that Twitter block an anti-Kremlin account that tweets government documents.