Opel Chief Executive Nick Reilly and labor leader Klaus Franz have called a joint press conference for 1200 GMT (8 a.m. ET) to inform on significant progress in the restructuring of Opel, the carmaker said on Friday.

The two sides have been negotiating over management's demand for 265 million euros ($329 million) in annual wage concessions, a key obstacle toward receiving possible loan guarantees from Germany worth over 1 billion euros.

Labor and management wanted to present an agreement before Tuesday, the next working day in Germany, when the steering committee of the German state rescue fund is due to discuss Opel's request for aid.

In exchange for agreeing to painful measures such as a wage freeze through 2014, the 50,000 strong European workforce has demanded that parent General Motors (GM) deliver airtight promises for investments in the manufacturing sites to prevent further production shifts to Korea.

The U.S. carmaker had reneged on a pledge in January not to shutter Opel production in Antwerp, prompting labor to demand collateral in the form of 10 percent of the shares in the company.

Detroit has balked at the terms, forcing Franz to propose a solution where the 10 percent would be held by a trustee who would gradually return the shares to GM as long as investment milestones are met over the course of the five-year business plan.

Investments for the Bochum plant for example would bolster its chances of manufacturing a second model next to the Opel Zafira minivan, based on the same global Delta compact platform used for the Astra.

Labor hopes GM would acquiesce to building the Chevrolet Orlando minivan in Bochum, which would represent a shift since GM had decided to move more and more European production to Korea, such as Opel's subcompact SUV originally due to be built in Antwerp.

(Reporting by Christiaan Hetzner; Editing by Erica Billingham)