Canadian-Austrian auto parts maker Magna International Inc. (MGA) still has to clear up some details regarding its bid for General Motors Corp.'s (GMGMQ) Adam Opel GmbH unit, German Economics Minister Karl-Theodor zu Guttenberg said Thursday.

Magna has set itself a "very ambitious goal" to finalize the takeover by next week, but a number of tasks still need to be done, zu Guttenberg said after a meeting with the economic ministers of German states.

The government acknowledges that there are other bidders for Opel, but the decision lies with the companies, not the government, he said, adding that the government is only indirectly involved via its trusteeship of Opel.

Other bidders include U.S. investment group Ripplewood, Chinese carmaker Beijing Automotive Industry Corp. and Italy's Fiat SpA (F.MI).

-By Beate Preuschoff, Dow Jones Newswires; +49 (0)30 - 2888 4122; beate.preuschoff@dowjones.com