By Jonathan Stempel

NEW YORK (Reuters) -Capital One (COF) was sued on Wednesday by New York Attorney General Letitia James, who accused the bank of cheating depositors with its flagship "high interest" savings accounts out of millions of dollars in interest.

In a complaint filed in Manhattan federal court, James said Capital One promised depositors one of the country's highest interest rates on their 360 Savings accounts, yet froze their rate at just 0.30% even as interest rates rose nationwide.

She said Capital One also kept those depositors in the dark in September 2019, when it launched 360 Performance Savings accounts, which gave new depositors interest rates that peaked at 4.35% while older depositors remained stuck with low rates.

James said Capital One never told 360 Savings depositors they could earn more by switching accounts, and even told employees to say nothing unless customers asked.

"Customers opened and maintained 360 Savings accounts based on Capital One's promises that they would receive 'one of the nation's best savings rates,'" the complaint said. "Instead, Capital One took advantage of its customers and hoped that they wouldn't notice."

The lawsuit accused McLean, Virginia-based Capital One of violating New York consumer protection laws. It seeks civil fines and restitution to customers.

Capital One did not immediately respond to requests for comment. Its 360 Performance Savings accounts now yield 3.6%.

The U.S. Consumer Financial Protection Bureau filed a similar lawsuit against Capital One on January 14, but dropped its case at the end of February after a change in leadership and U.S. President Donald Trump's return to the White House.

James noted that dismissal and said her lawsuit "seeks to ensure that Capital One does not escape accountability."

Last month, Capital One settled private nationwide litigation in the Alexandria, Virginia federal court over the 360 Savings accounts. Terms have not been disclosed.

Capital One expects to complete its $35.3 billion takeover of Discover Financial Services on May 18.

The case is New York v. Capital One NA et al, U.S. District Court, Southern District of New York, No. 25-04037.

(Reporting by Jonathan Stempel in New York, Editing by Nick Zieminski and Bill Berkrot)