Capital One is being sued by the US government’s consumer watchdog agency for “cheating millions of consumers” and not paying more than $2 billion in interest to holders of its high-interest savings accounts.

Federal regulators said in a lawsuit on Tuesday that the giant bank deliberately underpaid savings account interest, even as rates rose.

The U.S. Consumer Financial Protection Bureau is suing Capital One, claiming the company cheated customers out of $2 billion by misleading them.