iStock/Thinkstock(MOSCOW) — A massive ransomware attack struck computers across Europe Tuesday, affecting major companies in Russia and Ukraine as well as the world’s largest shipping firm, Maersk, according to the affected companies and government sources.

Ukraine appears to have been particularly badly hit, with the country’s government reporting that some of its systems, as well as those of key institutions including banks and telecom providers, had been affected.

The attack comes in the wake of the WannaCry virus in May, which seized control of hundreds of thousands of computers and spread disruption around the world.

As was the case with WannaCry, computers affected by this virus were locked with a statement telling people that they had to pay a ransom to unlock them.

Photos of the screens of computers and ATMs affected by the virus sent to ABC News and other media outlets showed the following message: “If you see this text, then your files are no longer accessible because they have been encrypted. Perhaps you are busy looking for a way to recover your files, but don’t waste your time. Nobody can recover your files without our decryption service.”

Russia’s state-owned energy giant, Rosneft, said it had also suffered a major attack, but in a statement on Twitter said it had succeeded in halting it.

Workers at another major Russian oil company, Bashneft, told the Russian newspaper Vedomosti the firm had also been affected.

An analyst at IB-Group told the Russian news site RNS that at least 80 companies had been affected in Russia and Ukraine.

In Ukraine, the virus struck the country’s government administration. The country’s vice prime minister, Pavlo Rozenko, wrote on Facebook that the cabinet’s office computers were all locked out.

Ukraine’s central bank said a number of banks in the country had been hit, as well as a state energy company. Some ATMs in the country were blocked and also displayed the lock-out screen. Ordinary Ukrainians reported being unable to use some banking services.

Local Ukrainian media reported that the country’s Borispol airport was also attacked, as well as Ukraine’s national rail company.

An advisor to Ukraine’s interior ministry, Anton Gerashchenko, called the cyber-attack the worst in the country’s history in a post on his Facebook page.

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