New York | The US Justice Department is preparing to sue Visa, accusing the financial services giant of breaking the law to shut out rival payment processors, two people familiar with the matter said.

At the centre of the lawsuit is payment processing technology, which connects a bank to a merchant whenever a purchase is made. The Justice Department plans to argue that Visa penalises its customers when they try to use competing services to process payments, said the two people, who spoke anonymously because the lawsuit has not yet been filed.