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KIEV, June 30 (Reuters) - Ukrainian state power distributor Ukrenergo was hit by another cyber attack on Thursday which used a computer virus different from one that hit Ukraine earlier in the week, the company's acting chief said.
The second attack did not affect Ukraine's power network, Vsevolod Kovalchuk told a news briefing on Friday.
Ukrenergo was an early victim of a cyber attack that began in Ukraine and spread around the world on Tuesday, knocking out thousands of machines, shutting down ports, factories and offices as it hit around 60 countries.
"The virus was slightly different, of a different nature, similar to WannaCry," Kovalchuk said about the second attack. "The effect from it was insignificant, as some computers remained offline."
WannaCry was the name of a global ransomware attack that struck in May.
Speaking about Tuesday's computer virus, Kovalchuk said that, according to preliminary data, it was activated during a software upgrade.
Cyber security firms are trying to piece together who was behind the computer worm, dubbed NotPetya by some experts.
A growing consensus among security researchers, armed with technical evidence, suggests the main purpose of the attack was to install new malware on computers at government and commercial organisations in Ukraine. Rather than extortion, the goal may be to plant the seeds of future sabotage, experts said. (Writing by Matthias Williams; editing by Jason Neely)