Ukrainian authorities said the country's top security body and a national news agency had been hit by cyber attacks.
Unidentified sources launched denial of service (DoS) attacks which are intended to make a machine or network resource unavailable to its intended users, officials said.
Last week the country's telecommunications system had come under cyber attack, with some Internet and telephone services severed after Russian forces seized control of airfields and key installations in Ukraine's Crimea region.
Security expert Dr Sally Leivesley has told Daybreak that the UK has become an "open business sign for criminals", after MPs warned today that it was "losing the war to cyber crime".
Dr Leivesley said: "Crimes have lifted up off the ground, they have now gone into the cyber highway and that's ungoverned space.
"What it means the economy is going to slow because it is an open business sign for criminals. It's the same as taking money out of our pockets.
"It's not that we are weak, it's because we are the leading financial centre of the world".
The NSPCC has welcomed a government drive to tackle cyber crime, after MPs warned today that the UK was "losing the war against online criminal activity".
Claire Lilley, safer technology lead at children's charity NSPCC, said: "It's vital that child abusers and other criminals do not view the internet as a wild west frontier where they can act with impunity.
"So it's good to see that the Government is taking cyber-crime seriously - in particular the issue of child abuse images being shared online."
Crime is changing and not falling at the rate that figures suggests, the chairman of the Police Federation of England and Wales said today, after an influential group of MPs found that UK was "losing the war against cyber crime" in a new report.
Steve Williams said:
The Government has set out recommendations in tackling the rise of internet crime, after a Home Affairs Select Committee found that the UK was being "too complacent" over online criminal activity.
According to the recommendations:
- More police officers to be trained in digital crime detection.
- Officers to be equipped with digital forensic skills.
- Government and the private sector to educate users and maintain awareness of the threat.
- Improved awareness among internet users could help tackle e-crime.
The UK is being "too complacent" about online criminal activity because the victims are hidden in cyberspace, the chair of the Home Affairs Select Committee said today, after it issued a warning that the country was "losing the war on internet crime".
Labour MP Keith Vaz said:
The UK is losing the war against internet crime, an influential group of MPs has warned. Despite being the preferred target of online criminals in 25 countries, the UK is still "complacent" towards e-crime as victims are "hidden in cyberspace", the Home Affairs Select Committee said.
The group of MPs said sufficient funding and resources for tackling online crime, which includes Identity theft, industrial espionage, credit card fraud and child exploitation, has not been allocated.
Tougher sentences for online criminals and improved training for police officers are recommended by the Committee to deal with the growing threat of cyber criminality.