BENTONVILLE, Ark. — Walmart Stores Inc. urged retailers to reject a proposed $6 billion settlement that Visa Inc., MasterCard Inc., and major banks have agreed to pay retailers for alleged fee fixing.

The settlement, reached earlier this month, had been considered a victory for retailers. It settled a lawsuit that claimed card issuers conspired to fix merchants’ fees for accepting credit cards. Retailers have long complained about the billions of dollars in ‘‘swipe’’ or ‘‘interchange’’ fees they have had to pay, which average about 2 percent of the price of a purchase.

But the world’s largest retailer said Tuesday that the settlement doesn’t restrict credit card issuers from continually raising fees merchants must pay when shoppers use their cards.

The Bentonville, Ark., company also says the settlement would require retailers to waive their rights to take action against card issuers.

Walmart joins Target Corp. in speaking out against the settlement.