Ukraine will block access to the Russian websites Vkontakte, Yandex and Odnoklassniki — all hugely popular in the country — under new sanctions measures, Kyiv Post reports.

Ukrainian President Petro Poroshenko signed a decree on May 16 blocking access to the websites and imposing a range of sanctions on Russian companies and individuals.

The decree enacts an April 28 decision of Ukraine’s National Security and Defense Council, which drew up a long list of physical persons and legal entities to be sanctioned. The sanctions officially come in action from the day the decree was published – also May 16.

The internet access to the websites, including Russia’s Mail.Ru Group and its mail.ru service will be blocked, along with access to Russian companies DrWeb and Kaspersky Lab, which provide computer virus protection services.

Earlier, economic sanctions were imposed on Russian television channels TV Center, RBK, NTV Plus, TNT, REN OTR, and others. Their assets were blocked, and the channels were banned from broadcasting in Ukraine.

Yandex, VKontakrte and Odnoklassniki are the leading websites in Ukraine in numbers of daily users. VKontakte is the most popular social network in the country, and the Yandex web-search engine is second only to Google in use. More than 5 million Ukrainians log in to the Odnoklassniki social network every day.

Even Ukrainian President Poroshenko has official accounts on VKontakte and Odnoklassniki publishing his latest news — on VKontakte, he has 463,000 followers. The Ukrainian market is Vkontakts’s second largest.