In a sign of banks' growing appetite for hostile takeovers, U.S. Bancorp's acquisition of California Bancshares reportedly was preceded by an unsolicited offer from a local rival.

San Rafael, Calif.-based Westamerica Bancorp, with $1.7 billion of assets, made an attempt last fall to acquire $1.6 billion-asset California Bancshares, according to a source with direct knowledge of the situation.

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