Sky News has reported that a letter has been circulated which praises the government for seeking a transition period after Brexit.
Part of the letter reads: "And as the UK makes progress towards establishing stronger trading links with markets like the US, India, Japan and Mexico, British businesses who know these markets well should stand ready to use their expertise and networks to cement future relationships.
"As business leaders, we have a duty to our shareholders and employees to continue to grow our businesses and ensure that they remain strong.
"As part of this we are also determined to see the UK continue to be a prosperous and united force for good in the world and are ready to play our full part to achieve this as Britain leaves the European Union."
However, it is thought that FTSE bosses have not reacted well to the directive from Downing Street.
The demands come as a business groups shot down the government's proposals for immigration after a leaked memo from the Home Office said firms could be required to undertake "right to work" checks on employees.