BROWNSTOWN TOWNSHIP, MI – Magna International Inc. and its Russian partner OAO Sberbank Rossii have reached an agreement in principle with General Motors Co. to buy a majority stake in the auto maker’s Adam Opel GmbH German subsidiary, although GM top’s executive says it will be at least a week before a final deal is struck.

GM President and CEO Fritz Henderson confirms receiving an “updated draft agreement” from the Magna investment consortium.

“I think we’ll spend the next few days evaluating it,” Henderson tells journalists today at the opening of GM’s new plant here, which will make battery packs for the upcoming Chevrolet Volt extended-range electric vehicle.

“(Magna) submitted (the draft) to the automotive task force in Germany, as well,” he adds. “They need to evaluate it. And then we need to take that feedback, as well as what the German government is prepared to do in terms of financing, and brief our board.

“I anticipate the briefing would be probably next week,” Henderson says.

Magna’s board of directors also must approve a deal before Opel trustees, who control a 65% stake in Opel, can give their final consent.

Although Magna appears to be the favored contender for Opel, reports say competing-bidder Belgium-based RHJ International Inc. still is in the running.

GM has said it does not prefer one bid over another, although the auto maker repeatedly has acknowledged the RHJI offer as the simplest to implement.

A deal giving the Magna consortium 55% of Opel requires tricky agreements of access to GM’s intellectual property, because the parts maker has supply contracts with other auto makers.