Britain could be forced to choose between the United States and China as it searches for post-Brexit trade deals, Liam Fox has been warned.

President Trump’s officials have indicated they plan to insert a “poison pill” clause into future American free trade agreements which would allow the White House to terminate them if partners strike a deal with Beijing.

The prospect has ignited fears that the UK must pick a side in the bitter dispute between the world’s two largest economies, limiting its trade prospects after leaving the European Union.

Dr Fox, the trade secretary, yesterday welcomed confirmation from Mr Trump’s chief trade negotiator that the US plans to open talks with Britain “as soon as it is ready”. Robert Lighthizer outlined proposals for a