Russia's top oil producer Rosneft said a large-scale cyber attack hit its servers on Tuesday and computer systems at some banks and the main airport in neighboring Ukraine were also disrupted.
A Moscow-based cyber security firm, Group-IB, said it appeared to be a coordinated attack simultaneously targeting victims in Russia and Ukraine, Reuters reports.
Besides, the Ukrainian central bank said a number of banks and companies, including the state power distributor, were hit by a cyber attack that disrupted some operations.
"As a result of these cyber attacks these banks are having difficulties with client services and carrying out banking operations," the central bank said in a statement.