Leaders of Femen, the Ukrainian women's rights group known for staging bare-breasted political protests, demanded government protection after two of them and a male associate were assaulted while on holiday in the Black Sea.
The two leaders, Anna Hutsol and Alexandra Shevchenko, and Viktor Svyatskiy, a colleague, were beaten on Saturday outside an apartment building in Odessa.
It was the fifth time in recent weeks that members had been assaulted. Femen says the attacks are part of a campaign to drive it out of the country.
The group called on Ukraine's minister of internal affairs, Vitaliy Zakharchenko, to provide round-the-clock security. "Otherwise Femen activists are in mortal danger," the group wrote, "the responsibility for which will inevitably fall on the security forces of Ukraine".
There was no immediate response from the government.
The group, which got its start in the university town of Khmelnytsky, now has headquarters in Kiev, the capital, and in Paris, along with branches in seven other countries. Members of the group, which says it opposes patriarchy in all forms, have staged topless demonstrations on an array of issues, including protests against prostitution, sex trafficking, organised religion, income inequality, domestic violence, female circumcision and authoritarian governments.
Photographs posted on the group's website on Sunday showed Hutsol with a swollen, red nose, a bloody eye and cuts above her lip, and Svyatskiy with welts on the side of his head, blackened eyes and a swollen lower lip.
Last month, Svyatskiy was beaten savagely near Femen's office in Kiev and spent two weeks in a hospital. Then, Hutsol was attacked outside her apartment on the same day, Shevchenko, two other Femen members and a photojournalist were beaten and detained overnight by the Ukrainian authorities.