The company claims the surcharge is necessary because larger bras are more difficult to construct, The Daily Telegraph reported Sunday.

Critics argue the fee is unfair, amounting to discrimination against curvy women.

Outraged shopper Beckie Williams said she organized a group on the social networking site Facebook to convince people to get Marks & Spencer to reverse the policy.

"Busty ladies, and anyone else with a vested interest in busty ladies, in fact anyone with a vested interest in simple justice, join forces to end this blatant discrimination," the Busts 4 Justice Internet group urges.

A Marks & Spencer spokesman said many women are "happy to pay a small premium" for the extra work that goes into making the bras.