CORRECTED - CORRECTED-UPDATE 3-US regulators seize two more banks

(Corrects percentage in fourth paragraph to .03 percent, not 0.3, as sent earlier)

By John Poirier

WASHINGTON, July 25 (Reuters) - U.S. regulators took over two banks on Friday and sold them to Mutual of Omaha Bank, the sixth and seventh bank failures this year as financial institutions struggle with a housing bust and credit crunch.

Two weeks after the Federal Deposit Insurance Corp seized IndyMac Bancorp Inc (IDMC.PK: Quote, Profile, Research, Stock Buzz), the Office of the Comptroller of the Currency said it closed First National Bank of Nevada and First Heritage Bank NA of California.

First National, characterized as undercapitalized, had total assets of $3.4 billion and $3 billion in deposits. First Heritage, described as critically undercapitalized, had assets of $254 million and $233 million in deposits, regulators said.

The FDIC said the cost of the transactions to its insurance fund is estimated to be $862 million, adding that the two failed banks represent just .03 percent of $13.4 trillion in total industry assets at about 8,500 FDIC-insured institutions.

The FDIC said the 28 offices of the two banks will reopen on Monday as Mutual of Omaha Bank. Over the weekend, customers can access their money by writing checks, using automatic teller machines or debit cards.

Mutual of Omaha Bank currently has more than $750 million in assets and operates 14 retail branches in Nebraska and Colorado with commercial lending offices in Dallas and Des Moines, Iowa, the FDIC said.

It is a subsidiary of Mutual of Omaha, a 99-year-old insurance and financial services company with more than $19 billion in total assets.