Ukraine's mobile phone infrastructure is under attack: with equipment installed in Russian-controlled Crimea interfering with the phones of members of parliament, a senior Ukrainian government official alleges.

The head of Ukraine's SBU security service told a press conference on Tuesday that the attack has been running for at least two days.

"I confirm that an IP-telephonic attack is under way on mobile phones of members of Ukrainian parliament for the second day in row," Valentyn Nalivaichenko told the new conference, Reuters reports.

Equipment installed within Ukrtelecom networks in the Crimea is blocking the phones of Nalivaichenko and his deputies, he said.

"The security services are now seeking to restore at least the security of communications," according to the security chief. "All state information security systems were unprepared for such a brazen violation of the law."

AFP also reports that Russian forces have also severed internet connections between the Crimean peninsula and the rest of Ukraine. Unidentified individuals reportedly seized local offices of state-owned telecommunications service provider Ukrtelecom, before cutting phone and Internet cables. The actions have severely degraded communication links.

Ukrainian naval communications stations around the port city of Sevastopol and power lines there have been sabotaged, AFP added.

Two Crimean government web portals were also offline, although the reason for this outage remains unconfirmed.

It's not all one way traffic. The website of the Russia Today news service was defaced by hackers for a short time on Saturday with the headlines of news articles changed so that references to “Russia” and “Russians" were replaced with the words “Nazi” and “Nazis”.

Russian forces seized strategic locations on the Crimean peninsula last week after a popular uprising in Kiev ousted pro-Russian President Yanukovych. Local militia set up roadblocks between Crimea, which has an ethnic Russian majority, and the rest of the Ukraine.

The use by Russia of electronic warfare against the Ukraine in the midst of escalating tensions within the country follows the pattern of earlier conflicts between Russia and its immediate neighbours.

For example, the military conflicts on the ground between Georgia and Russia back in 2008 over break-away regions of South Ossetia and Abkhazia - which have since become Russian protectorates - was accompanied by denial of service attacks and website defacements. ®