Anti-Lads' Mag protesters staged co-ordinated demonstrations at branches of Tesco across the UK on Saturday, demanding the supermarket chain end its sales of the "degrading, pornographic" magazines.

Branding men's magazines such as Zoo, Nuts and Loaded "deeply harmful", pressure groups UK Feminista and Object called on Britain's biggest supermarket chain to stop selling the publications.

Around 50 demonstrators converged on Tesco's central London store in Regent Street as part of a Lose the Lads' Mags campaign.

In an ironic nod to the retail giant's advertising slogan "every little helps", they unfurled a banner which read: "Sexism - every lads' mag helps."

Protest organiser Kat Banyard said Britain's largest supermarket chain must "show leadership" by refusing to stock magazines that treat women as "sex objects".

In Birmingham, Tesco in New Street agreed to remove the magazines from its shelves.

Further protests were held outside Tesco stores in at least 20 cities, including Norwich, Portsmouth, Northampton, Sheffield, Nottingham, Bristol, York and Glasgow.

In London, Banyard said the magazine's coverage of naked and near-naked images were demeaning to women and fuelled misogynistic attitudes and even violence against women.

The groups warned they would take legal action against Tesco, saying that exposing staff and customers to semi-pornographic imagery could be construed as sexual discrimination or even harassment.

"The problem is that lads' mags like Nuts and Zoo are deeply harmful - they're sexist, pornographic magazines that not only fuel attitudes that underpin violence against women, they can also breach equality legislation," she said.

"Tesco would never allow 'girlie calendars' on their office walls. Why are they choosing to stock degrading, pornographic lads' mags on their shelves?" said the campaign group.

"Exposing staff and customers to these magazines can actually constitute sexual harassment or sex discrimination under the Equality Act. We're clear that both ethically and legally lads' mags are well past their sell-by dates.

"Tesco need to step up and show leadership on this issue."

Silvia Murray-Wakefield, acting chief executive of Object, said: "Tesco has a 'no pornography' policy that their customers support. Instead of breaching it, they should lose the harmful, discriminatory lads' mags from their stores."

Domestic violence charity Women's Aid and the End Violence Against Women coalition have backed the campaign, while 18 lawyers specialising in equality and discrimination law have signed an open letter calling on retailers to stop selling them.

Earlier this month, Bauer Media Group, which publishes Zoo, and IPC Media, which publishes Nuts, withdrew their titles from the Co-op, after the supermarket demanded the products be sealed in 'modesty bags'.

The Co-op has confirmed it will cease to sell Nuts from September.