A behind-the-scenes struggle over UK policy towards China has begun, with Liz Truss, the trade secretary, backing plans, opposed by the Foreign Office, to give the British courts a role in determining whether genocide is happening in Xinjiang province.

MPs are due to vote in the new year on the Lords’ all-party amendment to the trade bill, which would give the courts a preliminary role in determining whether a genocide is being committed by a country with whom the UK might sign a trade deal.