About 300 masked pro-Russian militants wielding baseball bats have attacked a branch of a bank owned by a regional Ukrainian governor critical of Moscow.
The gang on Sunday attacked the Donetsk office of the powerful Private banking and metal industry holding belonging to billionaire Igor Kolomoisky who is also governor of the nearby region of Dnipropetrovsk.
They shouted slogans accusing Kolomoisky, 51, of being a "fascist" and "enemy of the people," according to an Agency France-Presse reporter on scene.
A leader of Ukraine's Jewish community, Kolomoisky is worth $US2.4 billion ($A2.60 billion).
Kolomoisky has been particularly vocal in his opposition to Russian President Vladimir Putin, attacking him as "not normal".
"He has gone mad with his mission to re-establish the Russian empire," he has said, vowing that "separatism will not pass in Dnipropetrovsk".
Putin himself responded by calling Kolomoiski "garbage" and a "scoundrel".
The oligarch has hit the headlines recently in Ukraine by offering a bounty of $US10,000 for each separatist held and handed over to the authorities.
