First talks between European unions and delegates from General Motors and Magna (MGa.TO) begin next week over plans to cut 10,500 jobs at Opel save labor costs in the hundreds of millions of euros.

In the coming week, works councils and trade unions will begin the negotiations over the future of the European sites and our jobs, a flyer distributed to German Opel workers on Friday said.

Two people familiar with the situation told Reuters that an initial round of informal talks would begin on Monday. Each country home to an Opel plant is expected to send one worker representative to Ruesselsheim to meet with negotiating partners from GM and Magna.

One of the remaining conditions for GM to sign a deal to sell a 55 percent stake in Opel to the Canadian auto parts supplier and its Russian partner Sberbank (SBER03.MM) is a pledge by labor to contribute to annual cost savings worth around 265 million euros ($390 million) for several years.

Local labor leaders at Opel's eight western European car and powertrain plants are all concerned how much volume they each might have to relinquish to benefit another site.

Yet the biggest job losses are expected to be in the Bochum factory in Germany -- which could lose production of the Astra compact and transmission production -- as well as Antwerp.

COUPLE HUNDRED EUROS DIFFERENCE

Opel's Belgian plant is in danger of being closed entirely now that GM looks like it plans to build two subcompact crossovers in China instead of Antwerp as originally promised a couple of years ago to replace the loss of the Astra concession.

We looked at it in detail but it just didn't make sense based on our own internal analysis, GM Chief Executive Fritz Henderson said on Wednesday during the Frankfurt auto show.

Efficiency metrics like the cost per vehicle did not show that Antwerp was better than Bochum, he had said, refuting speculation the EU might block the Magna deal because closing the Belgian site when Bochum was less productive was against internal market rules.

Bochum's production is 200 euros per car cheaper than in Antwerp, Bochum labor leader Rainer Einenkel said on Friday.

(Reporting by Christiaan Hetzner and Angelika Gruber)