Ukrainian president Petro Poroshenko has ordered the blocking of access to Russia's most popular social media websites and search engines.
In another round of sanctions in response to Moscow's annexation of Crimea, Mr Poroshenko's office published a decree which freezes the assets and bans the operations of hundreds of Russian companies in Ukraine.
The order also calls for blocking access to dozens of Russia's most popular websites for three years, including the search engine Yandex, social media network VKontakte and email provider Mail.ru.
All of them have substantial user numbers in Ukraine.
The websites were accessible in Ukraine on Tuesday afternoon and it was not immediately clear when and how the Ukrainian government would enforce the ban.
Unlike Russia, which has in recent years adopted and enforced a plethora of legislation to crack down on independent websites and online media, Ukraine does not have laws and regulations that would allow such a ban.
The decree dismayed many journalists and public figures in Kiev who saw it as an attempt to match Moscow's repressive legislation.
Mr Poroshenko "should not have copycatted the Russians, it will attract criticism from our international partners as well as at home", Kiev-based independent analyst Volodymyr Fesenko, said.
Most of the internet and media companies banned by Ukraine are privately owned and have grown from start-ups working out of a basement to major international businesses.
More than 11 million Ukrainians use the search engine Yandex, a Nasdaq-traded company that posted $14.5 million (£11.2 million) in net profit in the first quarter of the year.
