In her searing resignation letter addressed to deputy ambassador Michael Tatham and dated December 3, she accused politicians of a “reluctance to address honesty”, Presstv Reported.
“I have been increasingly dismayed by the way in which our political leaders have tried to deliver Brexit, with reluctance to address honesty, even with our own citizens, the challenges and trade-offs which Brexit involves; the use of misleading or disingenuous arguments about the implications of the various options before us; and some behaviour towards our institutions, which, were it happening in another country, we would almost certainly as diplomats have received instructions to register our concern.”
The 55-year old senior British diplomat in Washington said her position had become "unbearable personally and untenable professionally".
Her letter, seen by US broadcaster CNN, was said to have been shared widely with colleagues in the diplomatic service.
The Foreign Office said it would not comment on details of her resignation.
Ms Hall is the second senior diplomatic figure to quit the mission in Washington in dramatic fashion this year.
On September 10, the UK ambassador Lord Darroch was forced to step down amid a storm over leaked memos in which he branded Donald Trump's administration 'inept and insecure'.