Ukraine’s telecommunications system had been subject to a string of cyber-attacks most likely from Russia, Ukraine’s security agency said.
One of the attacks, reportedly starting soon after Russian forces gained control over airfields and important military facilities in the Crimea region, disrupted Internet and mobile phone communication channels of members of the Ukrainian parliament.
Though Ukraine’s officials did not reveal who was behind the attack, they said the attackers used equipment located in the Russian-controlled Crimea region.
In the latest incident, unidentified sources launched denial of service (DoS) attacks, which are intended to make a machine or network resource unavailable to its intended users.
"There was a massive DoS-attack on communication channels of the National Security and Defence Council of Ukraine which was apparently aimed at hindering a response to the challenges faced by our state," the Security and Defence Council said.
The Ukrainian state-run news agency Ukrinform reportedly suffered a similar attack.
The government has told ministries to take urgent measures to prevent their websites being blocked and ordered law enforcement bodies to investigate "evidence of cyber-attacks and punish those responsible in their implementation".