Ukraine opposition activist Dmytro Bulatov says he believes a pro-Russia group was behind his kidnapping and torture last month.

Bulatov went missing on Jan. 22 and resurfaced a week later, badly bruised and with part of his right ear cut off.

He told reporters at a news conference in Berlin on Saturday that his captors "spoke Russian, with Russian accents."

Bulatov says those who beat him were "professionals" and that they were particularly interested in finding out whether his group, Automaidan, was influenced and funded by the United States.

He says the captors also interrogated him about the car convoys Automaidan organized to picket the homes of powerful government and business figures, including Viktor Medvedchuk, the leader of a pro-Russia political organization.

Medvedchuk is close to Russia's President Vladimir Putin.