The U.S. government said on Friday it was deeply concerned over Russia's decision to block public access to networking site LinkedIn, saying it created a precedent that could be used to justify blocking other sites operating in Russia.

LinkedIn, which has its headquarters in the United States, is the first major social network to be blocked under a new law that requires firms holding Russian citizens' data to store it on servers on Russian soil.

Internet services analysts say other tech firms, including Facebook and Twitter, could also find access blocked unless they move data onto Russian-based servers.

Maria Olson, spokeswoman at the U.S. Embassy in Moscow, said Washington urged the Russian authorities to restore access immediately to LinkedIn, and said the restrictions harmed competition and the Russian people.

"The United States is deeply concerned by Russia’s decision to block access to the website LinkedIn," Olson said in a statement sent to Reuters.

"This decision is the first of its kind and sets a troubling precedent that could be used to justify shutting down any website that contains Russian user data."

On Friday, anyone attempting to access the LinkedIn website via Russian telecoms operator MTS saw a message in Russian saying: "Access to the resource you requested is restricted." Attempts to access the site via Vimpelcom, another major telecoms operator, were also unsuccessful.

Reads more at Reuters.