By Andrey Kuzmin
MOSCOW (Reuters) - Russia's Internet watchdog is working to block social networking sites rallying support for a mass protest next month backing Kremlin critic Alexei Navalny, activists said on Monday.
Navalny, a leader of the 2011-12 Moscow protest movement against President Vladimir Putin's rule, is facing charges of stealing 30 million roubles from two firms, between 2008 and 2012, in a case he has dismissed as politically motivated.
Putin's popularity reached record-highs this year, on patriotic sentiment after Russia annexed Crimea from Ukraine, but a currency crisis driven by Western sanctions and an oil price slump threatens economic stability and could strengthen his critics.
A colleague at Navalny's Rospil project, which investigates high-level corruption, said on Monday watchdog Roskomnadzor asked Facebook on Saturday to block a page announcing the protest at Moscow's Manezh Square, near the Krelmin, on Jan. 15.
"24 hours after I set up the page, Facebook blocked the event," Leonid Volkov wrote on the Rospil website. "Facebook did it at Roskomnadzor's request."
The site was still down on Monday. Roskomnadzor did not immediately respond to requests for comment. A spokeswoman for Facebook declined to comment.
On Monday, another Facebook page promoting the rally appeared with more than 24,000 people registered as attendees.
Currently under house arrest, Navalny is already serving a suspended five-year jail term for the timber conviction last year, which Kremlin critics also call a sham. The Kremlin denies their allegations that it uses courts to persecute opponents.
Navalny launched an unsuccessful campaign for the Moscow mayor's office last year.
A former employee of Russia's most popular social networking site, Vkontakte, said Roskomnadzor also sent 53 requests to it to block pages late on Sunday.
"They mainly try to block all pages, groups and events that mention the word Navalny," Nikolay Durov, a former employee of Vkontakte whose brother was ousted as founder of the site, said on his Vkontakte page.
Vkontakte spokesman Georgy Lobushkin said the firm constantly receives requests from state bodies to block content.
(This story has been refiled to fix typos in paragraph 11)
(Editing by Thomas Grove and Alison Williams)