The move by the Co-operative Group affects over 4,000 retail outlets and follows the introduction earlier this month of opaque screens on its magazine shelves as an interim measure until publishers introduce their own sealed bags.

Affected titles include Loaded, Front, Nuts and Zoo. The latter three are printed by Polestar.

The Sport newspaper has already agreed to cover up its editions sold through Co-op stores from the designated deadline.

Co-operative Group chief executive for retail Steve Murrells, said the move was a result of growing concerns from customers and members about the exposure to children of explicit sexual images in Co-op stores.

“Whilst we have tried to mitigate the likelihood of young children seeing the images with a number of measures in-store, the most effective way of doing this is for these magazines to be put in individual, sealed modesty bags,” he explained.

BPIF chief executive Kathy Woodward said that the move should not come as a surprise to either publishers or printers.

“This has been gaining traction for a while and especially more recently with David Cameron’s new measures on porn. It will be interesting to see how other retailers follow this.”

Woodward said that it was vital for printers to have close working relationships with publishers so that a solution could be worked out quickly without printers having to shoulder the costs of extra packaging.

“These printers of course have the capability to fulfil this need easily but it absolutely cannot always be their responsibility to absorb the added cost of something like this.

“If they have a long term contract with a publisher and suddenly that has to change it simply can’t keep biting into the printer profit margin because all that is actually doing is eroding the sustainability of our industry. If the client is demanding it then it needs to be passed down the chain and there must be some kind of agreement between the publisher and distributor on this.”

Responding to the announcement Women and Equalities minister Jo Swinson said: “Exposing children to lewd pictures that portray women as sex objects is not appropriate.

“That’s why The Co-operative’s decision to implement the Bailey review recommendation for publications with overtly sexual images on the cover to be displayed and sold in modesty bags is very welcome.

“Adults should be left to make their own decisions about what legal sexual images they look at, but the place for these is not next to the sweets at children’s eye-level. I hope other retailers will follow the Co-operative’s lead.”