Visa (V) and MasterCard (MA) are close to settling an antitrust case with the Justice Department over credit-card acceptance rules, The Wall Street Journal reported.

The settlement could allow merchants to steer customers towards cheaper forms of payment, a setback for a credit card industry that is already gearing up for new regulation, The Wall Street Journal said without naming its sources.

Merchants pay a processing fee every time a credit card is used. Cards that offer rewards like airline miles have higher fees, and when a merchant agrees to accept a company's cards, it has to accept them all.

The investigation focused on card company policies that stopped merchants from encouraging customers to use cards that have lower processing fees. Such "steering" is permitted under specific circumstances only.

Under the terms of the possible settlement, merchants would have more freedom to offer incentives to pay with no-rewards cards.