LONDON — Size is a sensitive subject in the clothing business. So when one of Britain’s most popular and affordable clothing giants was found to charge more for plus-size clothing, it was accused of imposing a “fat tax” on women.

The pricing by the store, New Look, revived a debate over whether the use of more fabric for the same outfit should logically cost more.

The controversy erupted when a New Look customer, Maria Wassell, said she discovered that a pair of green-striped trousers cost 15 percent more in all sizes above 16 (the equivalent of a Size 12 in the United States), which are considered plus sizes in Britain. (Even the phrase “plus size” is problematic to some, who argue that the industry’s labels are unrealistic.)

Ms. Wassell, 43, a retail supervisor from Kent, in southeast England, also discovered that a T-shirt and dress in standard sizes were cheaper than identical versions in the plus-size section, according to the local news media.