Capital One Financial (COF) and its Capital One unit have been sued by the US Consumer Financial Protection Bureau for allegedly "cheating" clients out of over $2 billion in interest payments on savings accounts, the regulator said Tuesday.

The bank "illegally deceived" customers by promising that its 360 Savings account offered one of the nation's "best" and "highest" interest rates, but it froze the interest rate at a low level while rates jumped around the US, the regulator said.

Capital One also created a similar product called 360 Performance Savings that paid out higher interest rates but did not notify 360 Savings accountholders about the new product, the regulator said. The CFPB alleged that the bank kept the accountholders in the dark about the new product, which cost them over $2 billion in lost interest payments.

Capital One Financial did not immediately respond to MT Newswires' request for comment.