Fiat SpA (F.MI) will make an offer for General Motors Corp.'s (GM) German unit, Adam Opel AG, by Wednesday, Fiat Chief Executive Sergio Marchionne said Friday.

"We will be able to make the offer by May 20," Marchionne said on the sidelines of a conference in Turin.

The German government has set May 20 as the deadline to submit offers for Opel.

Austrian-Canadian auto parts supplier Magna International Inc. (MGA) has also signaled its interest in GM Europe.

Italian labor unions and politicians have indicated growing concern of possible job cuts or plants downsizing in the peninsula from the positive conclusion of the ongoing Fiat talks with GM.

"The [Italian] workers shouldn't be concerned," Marchionne told reporters Friday. "We will do our best to avoid any damage from the current market conditions."

Fiat's CEO talked of a "European problem" amid the industry's overcapacity. The Italian government last week signaled it would continue to help Fiat as long as the car maker safeguards jobs at home by keeping plants open while it seeks to expand internationally.

Earlier Friday, Italian Industry Minister Claudio Scajola said Marchionne was ready to meet the government and labor unions to discuss a plan to create one of the world's largest car companies by merging its auto unit with some key GM assets.

"Once we complete our rather complex itinerary, we will go to Rome to speak to the minister [Scajola] to find a solution," Marchionne told reporters in Turin.

Company Web site: http://www.fiatgroup.it

-By Jennifer Clark and Liam Moloney, Dow Jones Newswires; +39 06 6976 6924; liam.moloney@dowjones.com

(Rosario Murgida of MF-Dow Jones contributed to this report)