Magna is seeking further multi-billion euro German government support if it takes over General Motors' Opel unit, German magazine Der Spiegel reported on Saturday.

The Canadian car parts group emerged on Friday as a favorite to acquire Opel after top German officials said the Canadian car parts group had submitted a better plan than rival bidders Fiat and RHJ .

Der Spiegel reported in an advance of an article to appear in Monday's edition that Magna wants the government to at least partially cover some of the 3-billion euro pension obligations.

In its draft plan presented to the government, Magna also wants Germany to provide loan guarantees of 4.5 billion euros in order to find and introduce an acceptable solution, Der Spiegel said, quoting from the draft.

Magna's plan also envisions raising output at Opel's main plant in Russelsheim to 250,000 cars per year from the 160,000 currently produced despite a reduction in staff.

Der Spiegel quotes Economy Minister Karl-Theodor zu Guttenberg saying that no decision has been taken yet: A risk analysis that removes all doubts has not yet been carried out. Thus there is still the option of a structured insolvency.

On Friday, Magna co-Chief Executive Siegfried Wolf laid out the company's Opel blueprint in detail. Wolf vowed to retain all four Opel plants in Germany and avoid mass job cuts, key criteria for politicians ahead of federal election in September.

German Foreign Minister and Vice Chancellor Frank-Walter Steinmeier described the Magna bid as the only sustainable plan among the three and said it would be examined closely.

But state premiers from the four German states where Opel has plants had diverging views. Most backed the Magna plan but Juergen Ruettgers of North Rhine-Westphalia (NRW) said it was unacceptable and needed changes.

Opel unions voiced opposition to the Magna plan, under which 10,000 jobs would be cut in Europe, including 2,500 in Germany.

Guttenberg and Steinmeier said a decision on a preferred bidder would come next week after ministers meet on Monday.

Both General Motors and the German government are in a race against time to finalize a sale of Opel. The U.S. government has given GM until June 1 to restructure its operations and prove it can be viable without state aid, or face probable bankruptcy.

The decision on who gets Opel will be taken by GM but the German government will also play a big role because it would likely supply billions of euros in financing guarantees.

Magna is competing against Italian carmaker Fiat and Belgium-listed industrial holding company RHJ International for Opel.

(Writing by Erik Kirschbaum; editing by Victoria Main)