The CEO of Japanese automaker Nissan asked Britain last month to promise compensation for any tax barriers resulting from the decision to leave the EU before it invested further in its plant in Sunderland, northeast England.
The British government announced last week it would trigger the formal legal process of exiting the EU by the end of March 2017, giving some further clarity to businesses affected by the vote.
But Prime Minister Theresa May has said she would not reveal her hand ahead of time in negotiations with European counterparts.