General Motors issued a thinly veiled warning to its Antwerp assembly plant in Belgium on Tuesday that production would be transferred to Asia or eastern Europe unless there was a significant reduction in costs.

But the Detroit-based carmaker gave a reprieve to a plant at Ellesmere Port, UK, by including it in plans for a €3.1bn ($4.2bn) investment to build a new small car to replace the Opel Astra.