The German economics ministry has denied a report that investment group RHJ International is emerging as the ministry's favourite to take over General Motors' European Opel/Vauxhall operations, despite the Magna International-led consortium being selected as the preferred bidder.

However, Kommersant business daily reported today that Magna and its Russian partner Sberbank had failed to agree a deal. The consortium was expected to agree on final terms of the deal with GM by yesterday.

A Magna spokesman told Kommersant that negotiations were continuing and that co-CEO Siegfried Wolf hoped to prepare a contract for signing this month.

Sberbank and Magna signed a framework agreement to buy Opel from GM in May under which Sberbank would get a 35% stake in the GM carmaker and Magna would receive a 20% stake. The two companies were offering EUR500m (US$700m) for the combined stake and expected to receive EUR4.5bn (US$6.25bn) in guarantees from the German government.

Kommersant said the consortium had been told it will need to improve its offer while GM  talked with other potential buyers including RHJ and Chinese corporation BAIC.

BAIC wants a 51% stake in Opel for EUR660m (US$900m) and is asking for fewer guarantees, according to the Wall Street Journal. RHJ has estimated the stake at EUR300m (US$420m) and is asking for only EUR3.8bn (US$5.3bn) in guarantees.

Separately Bild daily in Germany reported that RHJ had become the economy ministry's favoured bidder after presenting a revamped Opel bid proposal to the government on Wednesday, although this has been denied by the ministry.