Magna and its Russian partner Sberbank have reached an agreement with the management of General Motors to acquire a 55 percent stake in GM's European unit Opel, Magna Co-Chief Executive Siegfried Wolf told Reuters on Thursday.

The board of directors of Canadian automotive group Magna and of GM need to approve the deal before trustees formerly in control of a 65 percent stake in Opel can give their final consent, he said.

The agreement between Magna's consortium and GM -- which follows weeks of hard bargaining -- does not necessarily mean that competing Opel bidder RHJ International is out of the race, however.

GM's chief negotiator on the deal, John Smith, has said that the Belgian private equity firm had already reached an agreement with GM on Opel.

Nevertheless, the overwhelming support for Magna in Germany from key players like Chancellor Angela Merkel suggests that the Opel Trust will likely sign off on a deal only with the Canadian auto parts supplier and Russian lender Sberbank.

Magna is in the middle of negotiations over the financing for a deal, which includes an equity component of 500 million euros ($713.5 million) along with 4.5 billion euros in loans guaranteed by European governments.

GM Europe could not be reached immediately for a comment.