The scope of the problem is so bad insiders have said the issue is Brussels’ “worst-kept secret”.
Allegations include staff being asked to book prostitutes for their MEP bosses, young women being sent to dinners and bars to trade sexual favours for legislative backing and EU work contracts offered in exchange for sex.
Some MEPs are accused of paying for prostitutes on EU expenses which they do not have to publicly declare.
Male staff have also been bullied then sent on paid leave, according to claims.
Brussels-based news website, Politico, said 87 women and six men working for the EU have told them about being harassed, in what it described as “often terrifying experiences for the victims”.
Several women have come forward as part of the #MeToo movement which has evolved from allegations Hollywood movie mogul Harvey Weinstein raped multiple women and sexually harassed many more over a 30-year period.
Jeanne Ponté, assistant to French MEP Edouard Martin, last week revealed she has a notebook detailing a total of 50 instances of men working in the European Parliament behaving inappropriately towards her or a colleague since July 2014.
The 27-year-old claimed one of the most shocking times was being sent photos of herself which she had no idea had been taken.
She told Le Figaro: “A political adviser sent me photos of myself in the middle of the night, taken without my knowledge at a meeting.
“He keeps insisting on inviting me to dinner, despite my refusals.
“Another time a member of Parliament who blocked my way at the end of a conference, grabbed my waist, asked me if I had been here a long time and if I wanted to drink coffee with him.
“Another member asked me point blank if my tights are Chantal Thommass or Le Bouget – he has never commented on how one of my colleagues is dressed!”
Mr Martin revealed the existence of his assistant’s book in a bid to help stop the institutional sexism and harassment, and after encouraging Ms Ponté to testify, especially in the wake of the Weinstein allegations.
Another horrifying story included a senior MEP masturbating in front of a young staff member.
Gráinne Hutton, an intern with the EU’s Trans-Atlantic Business Council, tweeted last week as part of the #MeToo movement.
She said: “#Metoo. Because when it came to furthering my career in Brussels but seeing and working for him everyday, I chose to leave.”
Politico claims “over half” the stories of harassment it has been told occurred in the private sector, including at NGOs working with the EU.
European Parliament president Antonio Tajani reacted with “shock and indignation” in a statement responding to allegations of sexual harassment in Brussels.
He also committed to “increase awareness of the facilities already in place” – an advisory committee made up of MEPs to deal with harassment claims by assistants.
However, the Parliament acknowledge “so far, it has not received any formal complaints”.
Mr Tajani also said there is a brochure which explains harassment to MEPs, with posters plastered over Parliament buildings.