(Bloomberg News) A U.S. Bancorp unit asked a New York court to force Bank of America Corp.'s Countrywide Financial unit to repurchase more than 4,000 loans in a mortgage pool to repair breaches of contract related to improper underwriting.

The unit, U.S. Bank National Association, sued Countrywide yesterday in state court in New York, saying the lender agreed when it sold the pool in 2005 that it would repurchase all the loans within 90 days of receiving notice of a material breach. U.S. Bank is trustee for HarborView Mortgage Loan Trust 2005-10, which held the pool. The pool's original value was $1.75 billion, the bank said in court papers.

"Soon after being sold to the trust, Countrywide's loans began to become delinquent and default at a startling rate," U.S. Bank said in its complaint. "During the time period in which Countrywide originated the loans, it completely ignored its underwriting guidelines."

U.S. Bank asked the court to find that, as a result of a breach of its seller representation, Countrywide must repurchase all the loans. Or the court can order Countrywide to repurchase all defective loans, U.S. Bank said.

"U.S. Bank filed the lawsuit as trustee for HarborView," Thomas Joyce, a company spokesman, said. "We filed the lawsuit on behalf of the investors in the trust, at the direction of the investors in the trust."

"We are reviewing the complaint and do not have any comment at this point," Lawrence Grayson, a Bank of America spokesman, said today. Charlotte, North Carolina-based Bank of America, which was also sued, acquired Countrywide in 2008.

66% 'Breached Representations'

A review of loan performance found that in a sample of 786 loans "an extraordinary 66 percent of the loans breached one or more mortgage representations," according to the U.S. Bank complaint. The bank asked Countrywide to "either cure the breaches or repurchase the loans," according to the lawsuit.

"To date, Countrywide has failed to repurchase any loan put back to it by the trustee and has offered no basis for its refusal," U.S. Bank's lawyers said in court papers.

The case is U.S. Bank National Association v. Countrywide Home Loans Inc., 652388/2011, New York State Supreme Court, New York County (Manhattan).