Ukraine’s Opposition Bloc party is set to contest in court the president’s decree barring access to a number of Russian websites, party member and lawmaker Yuri Pavlenko said, TASS reports.

"We [the Opposition Bloc] have prepared a request to the Constitutional Court, in which we ask to cancel the unlawful presidential decree on blocking web resources, because it contradicts the current legislation and the constitution," the lawmaker told the 1+1 TV channel.

"The measures, envisaged by the presidential decree, go against the principles of the law on sanctions and create a dangerous precedent of Internet censorship," he said, adding that experts estimate the full implementation of the presidential decree to take several years and cost approximately $1 billion.

On Tuesday, Ukrainian President Pyotr Poroshenko enforced the decision of the Ukrainian National Security and Defense Council on expanding the list of Russian nationals and entities subject to Ukrainian sanctions and extending earlier sanctions. The blacklist includes 1,228 individuals and 468 legal entities.

Among the blacklisted entities are Russian social networking sites Vkontakte (VK) and Odnoklassniki (Classmates), and also e-mail services Mail.ru and Yandex search engine. Ukraine’s presidential press service said that Internet providers will block access to these websites in the country.

The move was condemned by numerous human rights bodies, including Human Rights Watch. Secretary General of the Council of Europe Thorbjorn Jagland said the ban violates the basic principles of the freedom of speech.