"I am quite confident after a top-level meeting of GM and Magna, where broad consent was reached," Forster told Frankfurter Allgemeine Sonntagszeitung (FAS) in an interview which will be published on Sunday. "It's only about details."

He did not give any details on the date, but said "it would be great if it worked out by mid July."

Sources had told Reuters in June that General Motors and Magna had set a target of July 15 for agreeing on the sale of a majority stake in Opel to the Canadian auto parts group and its Russian partner Sberbank.

The premier of the eastern German state of Thuringia, Dieter Althaus, told Berliner Zeitung am Sonntag he expected a deal between Opel and Magna to be reached this month.

Opel employs around 1,800 people at its plant in Thuringia.

German magazine Focus reported, citing sources close to Magna, that the Canadian auto parts group planned to separate Opel from its other businesses once the takeover was completed and may even float Opel on the stock market.

Magna is the frontrunner to buy Opel and Forster said Magna had a strong lead. But rival bidders are waiting in the wings.

Chinese automaker Beijing Automotive Industry Corp (BAIC) and Belgian holding company RHJ International are still hoping for a collapse in the talks in order to re-enter negotiations with GM.

Sources told Reuters on Friday that BAIC had submitted an indicative, non-binding offer for Opel and would make a binding offer by mid-July.

German Deputy Economics Minister Jochen Homann on Friday expressed skepticism over Magna's concept for Opel and said that vested interests praising the auto parts supplier's offer as the best left the German government open to "extortion.

Homann, who reports to Minister Karl-Theodor zu Guttenberg, stated no preference for any of the three current bidders.

(Reporting by Eva Kuehnen, Editing by Peter Blackburn)