"We've seen it with the formation of the EU commission that it's still difficult and that there is still work to be done on gender balance," Sannino said at the launch, in reference to the months-long horsetrading between Jean-Claude Juncker and national governments to send him more female candidates. In the end, only nine out of the 28 commissioners are female.

In practice, the caucus will pool female MEPs, EU commission officials and staff from the EU council and national embassies in Brussels, who will meet and try to promote more women inside and at the top of these institutions.

As for concrete proposals the new caucus will push for, Italian Socialist MEP Mercedes Bresso said that in her committee on constitutional affairs, there is already talk about changing the rules of how EU commissioners are appointed, so that each member state sends three candidates, male and female.

The caucus builds on an existing network of female parliamentarians from around the world - Women in Parliaments - championed by a former German MEP, Silvana Koch-Mehrin.

Mehrin said the gender gap in politics is higher compared to any other sector - 80 percent - hence the need to involve all female politicians and policy-makers at EU level.

EU commissioner Kristalina Georgieva will be the lead person for the commission. On Tuesday, however, she could not be present as she was stuck in the aforementioned budget talks.

Finland's ambassador to the EU, Pilvi-Sisko Vierros-Villeneuve, who oversees about 100 staff, out of which only 36 are male, spoke about the pioneering role of her country in Europe, as it was the first to grant women voting rights and has now reached parity in the public sector among men and women.

"We used to have a female president and boys in Finland would ask their parents 'Can a man actually become president?'. We recently elected a male president, so I guess they are less worried now," she quipped.

The ambassador of Rwanda also gave the example of his country - the only one in the world where female MPs outnumber male colleagues (64%).

This goes back to the genocide when lots of men were killed, but also further back in Rwandan history, when society was a matriarchy.