Russia's top oil producer Rosneft says its servers have been hit been a large-scale cyber attack, but its oil production was unaffected.

Russia's top oil producer Rosneft says its servers have been hit been a large-scale cyber attack, but its oil production was unaffected.

"The company's servers underwent a powerful hacking attack," the company said on Twitter.

"The company's servers underwent a powerful hacking attack," the company said on Twitter.