Protesters targeted Tesco stores across the country today to urge the supermarket giant to stop selling "deeply harmful" lads' mags.

Around 20 demonstrations took place outside Tesco stores across the UK including Glasgow, London, Northampton, Sheffield, Birmingham, Nottingham, Bristol and York.

The Lose the Lads' Mags campaign, led by pressure groups UK Feminista and Object, staged demonstrations in opposition to the retail chain's decision to continue selling magazines such as Nuts and Zoo to over 18s.

Displaying naked and near-naked images on magazine covers fuels attitudes underpinning violence against women and leave retailers facing the risk of legal action, the campaign group said.

Exposing staff and customers to such images could constitute sex discrimination or sexual harassment, it claimed.

Around 50 demonstrators gathered outside Tesco's Regent Street store in central London displaying a banner with the phrase: "Sexism - every lads' mag helps."

Speaking at the event, protest organiser Kat Banyard said Britain's largest supermarket chain must "show leadership" by no longer selling magazines which treat women as "sex objects".

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

"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. It is still sending out the message that it's normal and acceptable to treat women like sex objects because it's lined its shelves with magazines dedicated to exactly that."

UK Feminista and Object have branded Tesco's decision earlier this month to restrict their sale of lads' mags to over 18s as an "inadequate half-measure".

It comes amid increasing debate about the effects of sexual images on children, with David Cameron recently setting out a raft of reforms which will introduce family-friendly filters that automatically block internet porn unless customers choose to opt out.

The Co-operative has confirmed it will no longer sell Nuts magazine from early next month after the title rejected an ultimatum to use ''modesty bags'' or be removed from shelves.

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

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."

The central London protest also attracted the attention of comedian Heydon Prowse who played the role of a chauvinist presenter interviewing campaigners for BBC Three comedy series The Revolution Will Be Televised.

A Tesco spokesman said the company had listened to customers on the issue of selling lads' mags in its stores and introduced new measures including restricting sales to over 18s and ensuring the magazines are displayed on the back tier of shelves.

The supermarket chain also had assurances from publishers of Zoo, Nuts and Front that their covers would feature "more modest" images of women, he said.

The spokesman said: "We've had in depth conversations with our customers about this issue, and we're putting new measures in place based on what they have told us they want.

"We've listened carefully to the concerns raised by the campaign groups, but our priority is to make sure we meet our customers' needs and expectations.

"To do that, we have secured agreement from the publishers of Zoo, Nuts and Front that their magazine covers will be more modest from now on and the publishers of Bizarre will now supply the magazine in a bag.

"We are restricting the sale of these magazines to people over the age of 18, to reassure parents who do not want their children to be able to purchase these titles.

"And we will ensure these titles are always placed on the back tier of the magazine shelves, so that the cover is obscured with only the title visible."