New Delhi, Oct. 31 -- McDonald's McRib sandwich is facing fresh scrutiny over its ingredients, price and distinctive rib-shaped appearance, with a proposed class-action lawsuit accusing the fast-food giant of misleading customers into believing they are paying for a premium pork-rib product. The legal challenge has gained momentum after a US federal judge declined to dismiss key claims in the case, allowing the dispute to proceed.

The lawsuit has put the price of the limited-time sandwich under the spotlight. According to the complaint, the McRib cost reportedly as much as $7.89 before tax at some US outlets, making it one of the most expensive single-item options on McDonald's menu when available. The plaintiffs said its premium pricing...