Russian security services 'were involved in international cyber attack' - says Ukraine
Ukraine security services have claimed that Russian security services were involved in the recent virus attack on Ukraine.
The international cyber attack caused disruption for major organisations including advertising firm WPP, European bank BNP Paribas and parts of the Ukrainian government's computer systems.
Europol, which helps EU member states fight international crime, said the latest attack, the second in as many months, is more sophisticated than one in May that affected the NHS among others.
The group is monitoring the spread of the virus.
Europol executive director Rob Wainwright said: "This is another serious ransomware attack with global impact, although the number of victims is not yet known.
"There are clear similarities with the WannaCry attack, but also indications of a more sophisticated attack capability, intended to exploit a range of vulnerabilities.
"It is a demonstration of how cybercrime evolves."
In the attack, the virus encrypted computer files and then demanded payment of 300 dollars (£235) ransom in the online currency bitcoin in exchange for the captured data.
Ukraine was the worst affected by the ransom-demanding virus.