SAN FRANCISCO — A legal advocacy group filed suit against Wal-Mart Stores Inc. in San Francisco federal court Wednesday, alleging that the retailing giant discriminates against wheelchair users by placing check-out machines too high and out of reach.

“Because many customers who use wheelchairs and scooters cannot easily view, reach and use Wal-Mart’s [point-of-sale] terminals securely and independently, they must often process their transactions without knowing the information displayed on the POS viewscreen,” Kevin Knestrick of Berkeley-based Disability Rights Advocates wrote in the complaint.