Ukraine's government, National Bank and biggest power companies all warned of cyberattacks Tuesday. Airports and metro services in the country were also reportedly affected, though it appears they're victims of another massive ransomware outbreak that's spreading across the world fast and hitting a significant number of critical infrastructure providers.

Whispers of WannaCry abound, though security experts said a different breed, named Petya, is to blame. "[We're seeing] several thousands of infection attempts at the moment, comparable in size to WannaCry's first hours," said Kaspersky Lab's Costin Raiu. "We are seeing infections from many different countries." One firm, BitDefender, said it believed a similar strain called GoldenEye was actually responsible.

This morning saw major Danish shipping and energy company Maersk report a cyber attack, noting on its website: "We can confirm that Maersk IT systems are down across multiple sites and business units due to a cyber attack." And Russian oil industry giant Rosnoft said it was facing a "powerful hacker attack." Major British advertiser WPP said on Facebook it was also hit by an attack, while law firm DLA Piper was also reportedly affected. None had responded to requests for comment or stated what kind of attack they were under.

The impact initially appeared to be most severe in Ukraine, including major energy companies such as the state-owned Ukrenergo and Kiev's main supplier Kyivenergo. Government officials have reportedly sent images of their infected computers, including this from deputy prime minister Pavlo Rozenko:

Posted by the Deputy Prime Minister of #Ukraine, Pavlo Rozenko,
This is what's happening to government computers right now. pic.twitter.com/SxCudRt0AD

— Christian Borys (@ItsBorys) June 27, 2017