* Belgian holding company in advanced talks to buy Opel
* Spokesman declines to give financial details of offer
* RHJ International to have 438 million euros in cash by July 22
BRUSSELS, July 13 (Reuters) - Belgian holding company RHJ International said on Monday it was in advanced talks to buy a majority stake in General Motors Corp's European unit Opel.
RHJ's statement confirms a second rival to leading Opel contender Magna International, a Canadian auto parts group which has said it wants to agree a preliminary deal for Opel with its U.S. parent this week.
RHJ waited until Monday to confirm its interest in Opel because only now did it feel it was close enough to its goal to go public, a spokesman said.
"We felt we've reached advanced stages of negotiations, and we feel it is now appropriate to confirm these talks," RHJ spokesman Arnaud Denis said.
RHJ's shares dropped slightly after the news, trading down 0.2 percent to 4.10 euros at 0748 GMT.
While Magna has long been seen as the frontrunner for Opel, the German government -- which agreed to supply 1.5 billion euros ($2.09 billion) in bridge financing to Opel while a takeover was finalised -- has said the race remains open.
China's Beijing Automotive Industry Holding Co (BAIC) submitted a detailed bid for Opel earlier this month, according to documents seen by Reuters, laying out a plan to use Opel's brand and technology to tap the huge Chinese market.
RHJ plans just under 10,000 job cuts across Opel's European operations, one source familiar with Opel's plans told Reuters on Sunday.
German daily Bild am Sonntag reported on Sunday that RHJ would require some 3.8 billion euros ($5.29 billion) in government guarantees for Opel, less than the 4.5 billion Magna has said it needs.
RHJ's Denis declined to give financial details of its offer for Opel, or to say what it would mean for jobs or plant closures in Opel's German plants, its Antwerp site or the UK arm of the German carmaker, Vauxhall.
When its sale of a small stake in Egypt's Commercial International Bank is finalised by July 22, Denis said RHJ would have about 438 million in cash.
Opel's parent, General Motors, emerged from bankruptcy protection in the United States on Friday.
(Reporting by Anne Jolis; Editing by Erica Billingham)