By Maria Kiselyova and Alessandra Prentice
MOSCOW/KIEV (Reuters) - Vkontakte, the Russian version of Facebook (NASDAQ:FB), on Wednesday sent its millions of Ukrainian users instructions on how to circumvent a ban by the Ukrainian government.
Kiev on Tuesday forbade Ukrainian web hosts to provide access to popular Russian social networks, part of a package of restrictions on Russian internet firms that it said was intended to guard against cyber threats.
Critics said the move amounted to censorship; Vkontakte is the second most visited site in Ukraine and part of the web empire of Russia's Mail.ru Group (L:MAILRq), which estimated that 25 million Ukrainian users could be affected.
In a statement to Reuters, Vkontakte said it had sent its users a link to instructions for accessing its website once the ban comes into effect.
"We love our Ukrainian users and want you to be able to remain in touch with your friends and close acquaintances always," the message said.
The instructions included links to virtual private networks and to Tor software, which is designed to protect user privacy.
Ukraine said the ban was necessary to guard against Russian propaganda and cyber attacks following a collapse in relations due to Russia's annexation of Crimea from Ukraine in 2014 and an ensuing conflict with pro-Russian separatists in eastern Ukraine.
But Human Rights Watch (HRW) and the Council of Europe said restricting access to social media amounted to an attack on freedom of expression.
"This is yet another example of the ease with which President Poroshenko unjustifiably tries to control public discourse in Ukraine," HRW's Ukraine researcher, Tanya Cooper, said in a statement.
In Ukraine, a petition calling for the ban to be revoked was posted on the president's website on Wednesday, while small protests were held in Kiev and the eastern city of Kharkiv.
Shortly after announcing the measures on Tuesday, Ukraine said Russia had mounted a cyber attack on President Petro Poroshenko's website. Kremlin spokesman Dmitry Peskov on Wednesday dismissed the accusation as baseless.
Ukrainian lawmaker Serhiy Leshchenko said the authorities in Kiev had gone too far.
"If the aim was to fight Russian influence, there are ways to work within the networks rather than blocking them entirely," he said in an opinion piece published on the website of the Ukrainian magazine Novoye Vremya.
Ukraine's sanctions were aimed at a number of major Russian web firms, including Russia's largest internet group, Yandex (O:YNDX).