Ukraine blames Russian security services for recent worldwide cyber attacks
Ukraine says it has proof that Russian security services were involved in the cyber-attack that targeted businesses around the world earlier this week.
Moscow denied any involvement, adding that the allegations were "unfounded".
The virus, which disrupted IT systems across the globe, froze computers and demanded a ransom be paid in the digital currency Bitcoin, which is untraceable.
However, the attack also hit major Russian firms, leading some cyber security researchers to suggest that Moscow was not behind it.