Websites in both Russia and Georgia have been hit by cyber attacks since Georgia launched a major ground and air offensive to seize control of South Ossetia on Friday. Russia responded by sending in tanks and hundreds of troops.
"The DNS-servers and the site itself have been coming under severe attack," said Maxim Kuznetsov, head of the RIA Novosti IT department.
RIA Novosti's servers are now functioning as normal.
A top Russian diplomat accused foreign media on Sunday of pro-Georgian bias in their coverage of the ongoing conflict.
Russia says Georgian forces have killed around 2,000 South Ossetian civilians, mainly Russian nationals, since the start of the offensive, and that 34,000 locals have been forced to flee to Russia. In response to the Georgian attacks, Russia sent tanks and troops into the province, and carried out a series of air strikes on Georgian military targets.