Boston ? Backed by abortion rights groups, three Massachusetts women sued Wal-Mart on Wednesday, accusing the retail giant of violating a state regulation by failing to stock emergency contraception pills in its pharmacies.

The lawsuit seeks to force the company to carry the morning-after pill in Wal-Mart and Sam’s Club stores in Massachusetts.

The plaintiffs argued that state policy requires pharmacies to provide all “commonly prescribed medicines.”

Dan Fogleman, a spokesman for Bentonville, Ark.-based Wal-Mart, said the company “chooses not to carry many products for business reasons.”