They tied the protest with the screening of Ukraine is not a brothel, a documentary about the history of the movement by 28-year-old Australian film-maker Kitty Green.
The film also exposed a man - consultant Viktor Svyatskiy - as the mastermind behind the group. A message on the Femen website says Svyatskiy was badly beaten by Ukraine’s secret services this summer over his links to the group.
Femen, based in Kiev and Paris, has staged many carefully-crafted protests against sexual and political oppression since being established in 2008. Their slogan is, "Our mission is protest, our weapons are bare breasts".
They set up a branch in Rome in 2011. In one of their most high profile protests in Italy, the group attempted to confront former prime minister Silvio Berlusconi as he cast his vote in the national elections in February. They were promptly bundled out of the building by police screaming "Basta Berlusconi!" ("Enough Berlusconi!").
Watch the video of Femen's protest against Berlusconi: