Updated from 1:41 p.m.



, furious about a hostile takeover bid launched by


(ORCL) - Get Oracle Corporation Report

, is threatening to sue the database giant, Oracle CEO Larry Ellison said on Monday.

In a press release requesting a meeting with PeopleSoft's board to discuss the $5.1 billion offer, Ellison said: " ... a notice we just received with respect to your intention to commence litigation against us raises the concern that you have taken a negative position with respect to the merits and motivations behind our offer before you and the PeopleSoft board have taken the time required to consider (it)."

An Oracle spokeswoman would not elaborate on the note, and PeopleSoft did not immediately respond to requests for clarification.

Although PeopleSoft has not made a formal response to the $16-a-share proposal, CEO Craig Conway and CFO Kevin Parker have made it clear that they are not interested, and implied that Oracle is attempting to derail PeopleSoft's merger with

J.D. Edwards

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, a rival enterprise software developer.

Earlier On Monday, JDEC CEO Bob Dutkowsky reiterated his support for the PeopleSoft merger, and said a takeover by Oracle would be bad for software customers and possibly a violation of U.S. and European antitrust laws.

"Oracle's elimination of a competitor, its products and their ongoing development would reduce customer choice and product support and would leave many customers with greatly diminished options," said Dutkowsky. "This harm to customers is exactly what antitrust laws are intended to protect against."

PeopleSoft CEO Craig Conway, who informally rejected the $5.1 billion offer a few hours after it was announced on Friday, is still in Europe meeting with customers, but he may return early to discuss the bid with his company's board of directors, according to a PeopleSoft spokeswoman.

On Friday, Conway called the offer "atrociously bad behavior from a company with a history of atrociously bad behavior." Nevertheless, PeopleSoft must review Oracle's tender offer and make a recommendation to shareholders.

On June 3, PeopleSoft said it would swap stock initially worth $1.7 billion to acquire J.D. Edwards, a rival business software maker. Analysts have generally been positive about the combination, although integrating the two companies' products and cultures is likely to be difficult.

Oracle CEO Larry Ellison said he has not yet made up his mind about what he would do about the J.D. Edwards deal if his bid for PeopleSoft is successful.

The two deals are quite different. "Oracle appears more interested in PeopleSoft's maintenance stream and its customer base as well as eliminating PeopleSoft as a competitor," said Tad Piper, a U.S. Bancorp Piper Jaffray analyst. "PeopleSoft is seeking to broaden its product portfolio (into manufacturing) and expand its customer base and sales talents (more into the middle market) with its proposed acquisition of J.D. Edwards," Piper said in a morning note to clients. Piper Jaffray has no banking relationship with the companies mentioned.

Piper also notes that PeopleSoft has a "poison pill" in place that may make a hostile takeover difficult to execute. "We believe PeopleSoft has what is known as a blank-check preferred rights agreement, which enables the PeopleSoft board of directors to issue new preferred shares at its own discretion, without shareholder approval. We don't believe it would actually be executed (as poison pills rarely are), but it does necessitate Oracle negotiating with PeopleSoft's board," he wrote.

In recent trading PeopleSoft was down 2 cents a share, or 0.1%, to $17.80; Oracle was off 28 cents, or 2.1%, to $12.08, and J.D. Edwards shed 18 cents, or 1.4%, to $13.02.