Magna International Inc. (MGA) remains confident it will clinch the acquisition of General Motors Corp.'s (GMGMQ) core European unit, even as two rival bidders are gearing up efforts to grab Adam Opel GmbH for themselves.

Magna still is optimistic it will sign a deal with GM in the coming days, a person familiar with the matter told Dow Jones Monday.

But the person added that a Magna supervisory board meeting planned for July 14 has been postponed as several critical aspects of the transaction - such as intellectual property issues and access to growth markets - remained unresolved.

Canadian auto-parts manufacturer Magna emerged as front runner to buy Opel and its British brand Vauxhall after it signed in May a non-exclusive memorandum of understanding to acquire a majority stake as part of a bid backed by Russia's Sberbank Rossia (SBER.RS) and automaker OAO GAZ Group (GAZA.RS).

The bid is bolstered by EUR1.5 billion in bridge financing provided by the German government to keep Opel afloat as GM filed for bankruptcy in the U.S. Opel's powerful labor unions have voiced their support for Magna's offer.

But in recent weeks, RHJ International SA (RHJI.BT) and Beijing Automotive Industry Holding Co. Ltd. boosted their efforts to catch up with offers that would require lower government financing guarantees than Magna.

GM signed the tentative agreement with Magna but expects to put "two or three fully-formed proposals" to the trust overseeing the European operations and the U.S. auto task force, according to a person familiar with the company's plans. GM Europe is not expected to name a preferred bidder ahead of the decision, the person said.

RHJ, a Belgium-based investment group, Monday announced in a statement that talks with GM were at an "advanced stage," but didn't offer further details.

While speculation has circulated that RHJ's chances may be better than initially thought, the company earlier this month reported a EUR1 billion net loss for the year ended March 31 that cast doubt on its financial clout.

But RHJ claims that it has the financial muscle for the deal. "We have a large cash position," said Arnaud Denis, a spokesman for RHJ in Brussels.

Last week, China's BAIC detailed its interest Opel - it wants to get its hands on the U.S. automaker's technologies, including alternative drive trains.

BAIC said in a document outlining its offer that access to GM's advanced technology was the "key driver" for its bid. According to the document, GM would have to "license all alternative propulsion technologies (i.e. hybrid, fuel cells)" to Opel, including the new company's planned Chinese operations.

BAIC plans to invest $2.25 billion in Opel in China to ramp up production there by 2015. The document, which was reviewed by Dow Jones, is addressed to GM, dated July 2 and signed by BAIC Chairman Heyi Xu. BAIC is offering EUR660 million in equity for a 51% stake in Opel, with GM retaining a 49% stake.

But BAIC's offer is raising concerns about technology transfer. According to an internal document from the German economics ministry seen by Dow Jones Monday, Opel could become too reliant on the Chinese government if BAIC gets the nod to take over the company.

The document, dated July 3, said a new Opel could get into a "difficult dependency" on Beijing if government-owned BAIC succeeded.

Company Web site: www.opel.de

-By Christoph Rauwald, Dow Jones Newswires; +49 69 29 725 512; christoph.rauwald@dowjones.com

(Katharina Becker, Andrea Thomas, Alessandro Torello, Doug Cameron and Adam Cohen contributed to this report.)