Three women staged the protest in Barcelona outside the Mobile World Congress, the world’s largest exhibition for the mobile phone industry, where Facebook founder Mark Zuckerberg was set to give a talk.
They carried signs denouncing Facebook's policies with phrases such as "Censored for feminism" and a thumbs-down symbol drawn across their bare chests.
One woman, carrying a sign declaring "Facebook sexism is one of our terms and conditions", also had the phrase "Zuckerberg get off my nipples" written on her chest and stomach.
Femen is known for its topless activists, most recently seen outside of Spain’s parliament building to protest against the country’s new 'gag law', and has complained about Facebook blocking images of its events. The group has described its form of protest as "sextremism serving to protect women’s rights".
The protest coincided with the beginning of a talk by Zuckerberg inside the exhibition centre and lasted a few minutes, with no police getting involved, according to Catalan daily La Vanguardia.
Note: Due to pressure from social media and advertising networks, The Local regrets to say it has no option but to censor photos containing female nipples.