A number of women’s sport groups have urged International Handball Federation President Hassan Moustafa and European Handball Federation President Michael Wiederer to resign over "blatantly sexist" uniform regulations.The Norwegian women’s beach handball team were fined €1,500 (£1,295) at the European Championships last month after refusing to wear regulation bikini bottoms during their bronze-medal match against Spain.Players had requested to wear shorts during the tournament, claiming bikini bottoms made them feel unnecessarily sexualised and uncomfortable when they were on their periods. But organisers rejected their plea, citing EHF rules which require female players to wear bikini bottoms with a side width "of a maximum of 10 centimetres."Assist, an Italian organisation that promotes and defends the rights of female athletes, joined the Alice Milliat Foundation in France, Discover Football in Germany and four other associations in writing to Moustafa and Wiederer. In their letter, they wrote that both the IHF and EHF "have established an embarrassing point of no return regarding their image as international sports institutions".Assist President Luisa Rizzitelli also spoke to The Guardian about the beach handball uniform regulations."This is a blatantly sexist custom that needs to be eliminated," she said, adding: "Not only did they not immediately drop the rule [after the incident with Norway], but they confirmed the fine – that’s the shameful thing."

In response to the uproar caused by the uniform regulations last month, Wiederer announced the EHF would be looking to alter the rules for female athletes. The IHF have since revealed a proposal for new uniforms could be presented to the body’s Council in November.

Tennis legend Billie Jean King was among those criticising the decision to punish the Norwegian team, demanding the "sexualisation of women athletes must stop". Popstar Pink also waded into the discussion, voicing her support to the Norwegian beach handball team on Twitter and offering to pay their fine.

"I'm very proud of the Norwegian female beach handball team for protesting sexist rules about their uniform. Good on ya, ladies. I'll be happy to pay your fines for you. Keep it up." The singer also suggested the European Handball Federation should be "fined for sexism."

The Norwegian Handball Federation, which had previously made an official complaint against the bikini bottom rule, ultimately paid the fine.