Bank of America Corp., the biggest U.S. bank by assets, was sued by investors in mortgage-backed bonds who are seeking to force the bank to buy back loans underlying their securities.

Bank of America's Countrywide Financial unit breached representations and warranties about the loans, which it originated, the investors said in the complaint filed today in New York State Supreme Court in Manhattan.

“Each of these breaches of representations and warranties materially and adversely affected the interests of both the trust and plaintiffs in those mortgage loans,” they said.