Feminist protesters have begun vandalising the new open-air street urinals in Paris, labelling them sexist and discriminatory.

Several of the eco-friendly urinals have been placed in public spots in recent months as an experiment to counter Paris’s problem of urine-soaked pavements.

But protesters in recent days targeted two on the Île Saint-Louis and near Gare de Lyon station – plastering them with stained sanitary towels and tampons, then blocking them with concrete.

Notes left behind attacked Paris authorities for encouraging men to unzip and relieve themselves without cover in open public spaces – even though public breastfeeding still elicits scorn.

Un grand 👏 aux féministes subversives pour cette action contre les "uritrottoirs" - Paris 23 août 2018 pic.twitter.com/nC6G92pbJn — M.A.L.I (@MALImaroc) August 24, 2018

Police are investigating. No group has claimed responsibility, but the feminist protest group Femen denied involvement.

Equality campaigners and women’s groups, along with local residents and parents, have complained that the open-air urinals are sexist and discriminatory.

Without stalls or cover, the five experimental sites carry prominent signs showing a man proudly relieving himself in public. But no extra facilities are provided for women.

Uritrottoir on the banks of the Seine. Photograph: Thomas Samson/AFP/Getty Images

Feminists warned that authorities were sending the message that men owned the streets and could freely expose themselves in public – something at odds with debate in the wake of the #MeToo anti-harassment movement over how public spaces should allow women the right to feel at ease in the street.

Gwendoline Coipeault of the feminist organisation Femmes Solidaires said: “It is not just men who occupy the public space, but also women and children, who might not want to see men publicly urinate.

“These urinals are designed to comfort men and reinforce the idea that women aren’t welcome in the public space. It is discrimination and reinforces the stereotypical, sexist idea that men can’t control themselves in any way, including their bladders.”

She added: I don’t know a single woman who regularly goes to Paris who hasn’t witnessed a man urinating in public – openly on streets, in the metro – which reinforces a feeling of insecurity.”

Coipeault said there were already hundreds of closed public toilets in Paris and men should instead be encouraged to use them, as women did, rather than being invited to unzip outside.

Chris Blache, a feminist and urban anthropologist, was not surprised by protests against the urinals. “Frankly, these urinals are a provocation to women,” she said. “It’s not about prudishness, it’s about gender equality in the public space.”

She warned that far from solving Paris’s problem of street urination, the open-air urinals reinforced the notion that it was fine for men to expose themselves and urinate in public, while women were still criticised for breastfeeding outside.

Blache, who has advised the Paris authorities on gender-equality in town planning, said she was not attacking the mayor, Anne Hidalgo, but rather the institutional sexism of technical teams who had not thought through the message they were sending.

In recent days, some male commentators suggested women should simply use the open-air urinals standing up with the aid of a funnel. Blache dismissed this. “If a woman did that, it would be seen as a provocation and certainly not as the simple need to publicly relieve yourself after drinking too much beer, as it is seen for men.”

Police handed out 5,000 fines to people caught urinating against walls or on pavements in Paris in the first half of 2018 – almost all men. But with 450 self-cleaning public toilets across the city, many open 24 hours a day, feminists said the extra public urinals specifically for men were sexist and unnecessary.

Chloé Humpich from Paris city hall insisted the city was committed to gender equality. “Paris would never promote a measure that discriminates against women ... We regret that these urinals have been damaged. We hear the criticisms and we’re conscious of taking women’s views into account.”