He has been moved to intensive care after police reportedly tried to remove him.
The 35-year-old has had surgery after claiming he had been abducted and held captive, beaten and tortured.
The Interior Ministry has issued a wanted notice, saying it considers him both a victim of kidnapping and a suspect in organising mass disorder.
“Despite the fact that there is not a single spot on my body that doesn’t hurt; despite the fact that my face was cut and they threatened to prick one of my eyes, they cut off a piece of my ear, crucified me, nailing me to a door, and beat me viciously at the same time, I had a sack on my head – despite all of these things and other cruel torture as well, I want to say that we won’t be intimidated, and nothing will stop us,” Bulatov said from his hospital bed.
The activist was one of the leaders of anti-government protest motorcades called “Auto-Maidan”, in which scores of cars would drive to the homes of Ukrainian leaders.
He was reported missing on January 23 and resurfaced last Thursday in the woods outside a village.
The authorities have suggested the activist’s disappearance might have been a deliberate ploy by the protest movement to inflame an already highly tense situation in the country.
The opposition talk of death squads operating in Ukraine and want an international investigation.
Outside the hospital, former Independent MP Taras Chornovil said there was enough evidence, in Bulatov’s case and those of others, for the International Court of Justice to mount a prosecution.
Bulatov’s supporters are organising round-the-clock protection for the activist and have asked police to hold back.
Ukraine’s anti-government protests began in November after President Yanokovych ditched a planned accord with the EU, instead turning to Russia for economic aid.
The president has ordered the repeal of a new law restricting protests, agreed to an amnesty for protesters and accepted the resignation of members of his cabinet.
Yet despite the concessions, mistrust on both sides appears higher than ever.