The websites of major Russian news outlets including TASS, Izvestia and Kommersant have been hacked on Monday.
The websites could not be opened earlier, with many displaying error pages.
The press service of the Izvestia newspaper confirmed the hack, adding that everything is currently being done to ensure citizens' access to information, Russia's RIA Novosti reported.
The editor-in-chief of Kommersant, Vladimir Zhelonkin, also confirmed the hack.