Update: The Chinese government has now confirmed this date.

The iPhone looks set to be launched by China Mobile – the biggest carrier in the world’s biggest country – on Wednesday 18th December, reports the WSJ. While neither the carrier nor Apple have made a definitive announcement, China Mobile has said this is the date it will “introduce a new brand.”

China Mobile posters for the iPhone 5s and 5c had leaked as long ago as September, but the deal itself has been a long time coming. It’s a hugely important one to Apple, with analysts estimating that Japan and China between them will be worth an extra 38M iPhone sales.

One analyst quoted by the WSJ believes the potential number is very much larger.

It has been claimed that China Mobile already has 42M iPhone users, purchased at full price from other sources and then used with China Mobile SIMs.

The exact terms of the deal between Apple and China Mobile are unlikely to be made public, but Bloomberg had suggested back in September that Apple may have found itself in an unusually weak bargaining position given the importance of securing this deal.