Oracle has rejected BEA Systems' proposed purchase price of $21 per share, calling it "impossibly high" for Oracle or any other company to pay.

In a letter to BEA's board dated Oct. 25, Oracle again urged the company to accept its offer of $17 per share, an amount that Oracle said it was "unwilling to increase."

"The $21 per share price is a multiple of nearly eleven times BEA's last twelve months' reported maintenance revenues," wrote Oracle President Charles Phillips. "Nobody would seriously consider paying that kind of multiple for a software company with shrinking new license sales."

He noted that Oracle was the only company making an offer for BEA. "Apparently no other companies think that BEA is worth $17 per share, let alone $21 per share," Philips wrote.

Oracle again urged BEA to put its offer to a shareholder vote. Oracle's bid of $17 per share values BEA at about $6.7 billion. A price of $21 per share would value it at $8.3 billion.

Oracle said it had an obligation to its own shareholders to "exercise price discipline when evaluating acquisition opportunities." It reminded BEA of its deadline of Sunday evening to accept the offer, after which it will "move on" and consider other acquisitions.

Oracle made its surprise bid for BEA on Oct. 12, hoping to strengthen its line of middleware products and grow its customer base. BEA, which had been under pressure from investor Carl Icahn to sell, quickly rejected the offer as too low, and on Thursday came back with its suggested higher price. Oracle's offer "significantly undervalues BEA" and is not in the best interests of BEA's shareholders, it said on Thursday.

BEA officials weren't available for comment on Oracle's latest letter.