Haggling over future development work has delayed General Motors planned sale of its European operations to the PSA Group.

The crux of the issue lay in the work volume going forward at Opel's Development Center (ITEZ) in Rüsselsheim as there is overlap with PSA's own development centers which employ 13,000 people. Employee information sessions which were supposed to begin this week have been postponed as Wolfgang Schäfer-Klug, Chairman of the Opel Works Council, said the issue is not disputable.

German labor union IG Metall and the works council want 7,700 jobs at ITEZ guaranteed before the sale goes through, including continued development work for General Motors which could account for 30% of Rüsselsheim's output through 2020.

The kerfuffle comes after PSA announced in early May that Opel's next-generation Corsa due in 2019 will be developed using a PSA platform to increase cost advantages, instead of GM's platform as originally planned. In response, Opel contends that it should still develop the next-generation Corsa and continue with plans to build a large SUV based on the Insignia's E2XX platform.

According to German publication Automobilwoche, a spokeswoman for the works council emphasized that there was no disagreement between any of the negotiating partners, but the matter is extremely complex and ratification will take longer than expected.

GM's European assets for sale were supposed to be transferred to a new company titled Opel Automobile GmbH this week, but that has been postponed indefinitely. Opel still expects the deal to close before the end of 2017.