(Reuters) - Capital One was sued on Tuesday by the U.S. Consumer Financial Protection Bureau, which accused the bank of illegally avoiding the payment of more than $2 billion in interest to consumers who held its flagship "high interest" savings account.

In a complaint filed in the Alexandria, Virginia federal court, the CFPB said Capital One promised account holders that their 360 Savings accounts provided one of the nation's best interest rates, but then froze the rate at a low level even as interest rates were rising nationwide.

(Reporting by Jonathan Stempel, Editing by Louise Heavens in New York)