A senior British diplomat in Washington has resigned, saying she can no longer “peddle half-truths” about Brexit.

Alexandra Hall Hall, the lead envoy for Brexit at the UK embassy, said her Government’s arguments were “misleading and disingenuous”.

In her resignation letter Ms Hall Hall, 33, said her position had become “unbearable personally and untenable professionally”.

She wrote:

“I am also at a stage in life where I would prefer to do something more rewarding with my time, than peddle half-truths on behalf of a government I do not trust.

“I have been increasingly dismayed by the way in which our political leaders have tried to deliver Brexit, with reluctance to address honestly, 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.

“It makes our job to promote democracy and the rule of law that much harder, if we are not seen to be upholding these core values at home.”

She continued: “I took this position with a sincere commitment, indeed passion, to do my part, to the very best of my abilities, to help achieve a successful outcome on Brexit.

“Each person has to find their own level of comfort with this situation.

“Since I have no other element to my job except Brexit, I find my position has become unbearable personally, and untenable professionally.”

A Foreign Office spokesman said:

“We won’t comment on the detail of an individual’s resignation.”