More now on the breaking news that Ukraine has been targeted by a large scale cyber-attack.
A minister has told the Interfax news agency that services for several Ukrainian institutions, including the health, security and foreign ministries, have been taken offline in a so-called DDOS attack.
He added that several banks have also been affected by the outage.
DDOS attacks, or Distributed Denial of Service, aim to overwhelm websites by flooding a network with fake traffic and preventing it from communicating as it normally would.
Ukrainian authorities said this week they had seen online warnings that hackers were preparing to launch major attacks on government agencies, banks and the defence sector.