A founding member of the prominent protest group Femen, Oksana Shachko, has died in Paris in an apparent suicide, fellow members say.

"RIP. The most fearless and vulnerable Oksana Shachko has left us," a post on the Femen website said. "We mourn together with her relatives and friends and [await] the official version from the police."

"At the moment it is known that ... July 23, Oksana’s body was found in her apartment in Paris. According to her friends, she left a suicide note," the post said.

"As far as I know, she was concerned that everything is going badly in the world," Femen co-founder Anna Hutsol told RFE/RL's Ukrainian Service on July 24.

The second secretary at the Ukrainian Embassy in Paris, Oksana Lovha, confirmed Shachko's death to Current Time TV, the Russian-language network run by RFE/RL in cooperation with VOA.

There was no public comment from French authorities, and Lovha said Ukrainian diplomats were awaiting further details from police.

Founded in Ukraine a decade ago, Femen is known mainly for protests in which activists often bare their breasts -- sometimes exposing slogans written on their skin -- and disrupt political events or gatherings.

Femen activists have rushed politicians such as Russian President Vladimir Putin and Czech President Milos Zeman, and public figures like American comic Bill Cosby.

Often directed at leaders they describe as dictators or oppressors, their protests have also taken other forms and targeted issues such as the environment.

A native of Ukraine who had lived in Paris in recent years, Shachko, 31, was one of a group of Femen activists who rushed Putin and German Chancellor Angela Merkel in Hannover, Germany, in 2013.

"Oksana fought against injustice, fought for equality, fought like a hero for herself and for other women," said a post on the Femen website said.

"Oksana is no longer with us, but she is here, she is everywhere," it said. "Oksana ... is in each of us, she is in FEMEN, and she is in the history of feminism."

Femen said in 2011 that Shachko was among three members seized by security officers after staging a topless protest mocking Belarusian President Alyaksandr Lukashenka.

It said the officers forced them to strip naked, poured oil over them, threatened to set them on fire, and cut off their hair.

Femen has said that Shachko was abducted again during a visit by Putin to Ukraine, and a lawyer for the group said she was beaten and briefly hospitalized.

Femen now has branches on at least four continents.

BBC contributed to this report.