Opel boss Nick Reilly seemed in bullish mood last week at the Paris motor show when he confided two possible investors might be unveiled this week for the Antwerp plant.

But, one swift email later, and Reilly seems to have poured an awful lot of cold water on any rescue plan by those potential bidders, one of whom Opel deemed to have come with too many conditions.

But Opel’s ACV Metal union at the plant – representing some of the 1,300 workers – does not even know the identity of the bidders apart from that one is Chinese.

ACV claims Opel has not detailed any offer from these mystery Chinese investors and is now requesting the company divulges their identity so that direct contact can be made.

For the moment GM is keeping quiet on identities – Chinese or otherwise – but the unions are very keen indeed to know who they might be.

It looks like a final throw of the dice from the labour organisations. The plant, where half of the employees have already departed, has been earmarked for disposal for some time by Opel, which has undergone some radical restructuring across Europe to cut capacity.

One pan-European union official told just-auto that, if no industrial partners could not be found he feared the Antwerp site could be turned towards warehousing – the fate of some axed US GM plants – or even car parks.

ACV said any potential Chinese investor had been given “code names” but, now Opel has decided to stop the formal hunt for an industrial investor, why the secrecy?

A conference call amongst multiple European unions – including those in the UK, Germany, Spain, Poland and, of course Belgium – was held earlier on Tuesday, at which ACV noted discussion of “some action” was being aired.

What that action might constitute has not yet been revealed but, if Opel was to open the books to the unions, might this not throw some sort of lifeline to Antwerp?

Opel has clear reservations about the bids it has received, but maybe there is a chink of light for the unions to at least give it a go?