(Bloomberg) -- Walmart Inc. and one of its financial technology partners allegedly opened expensive bank accounts for delivery drivers without their consent, a US consumer protection agency said on Monday.

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The Consumer Financial Protection Bureau claimed that Walmart and Branch Messenger Inc. required the delivery drivers to be paid through costly accounts. The agency sued the two companies in the US District Court for the District of Minnesota, according to a statement.

"Walmart made false promises, illegally opened accounts, and took advantage of more than a million delivery drivers," CFPB Director Rohit Chopra said.

Neither Walmart nor Branch Messenger immediately responded to a request for comment.