Boris Johnson should have the power to appoint ministers who are not MPs or peers, an influential body set up to help overhaul Whitehall is set to recommend.

The Commission for Smart Government, set up last year to find ways of improving the functioning of Whitehall, will next week launch a report calling for prime ministers to be given more flexibility over ministerial appointments.

The commission, which is chaired by Nick Herbert, a former Tory minister, is also said to be preparing to recommend that a “Prime Minister’s department” be established, which would give Mr Johnson access to thousands of civil servants.

According to The Times, the new department would include a Treasury Board comprising of the Prime Minister’s officials and chaired by the Chief Secretary to the Treasury, in a move that would weaken the Exchequer’s grip over Government spending.

The report is due to be launched on July 12, and will be attended by Michael Gove, the Chancellor of the Duchy of Lancaster, who is overseeing the Government’s reforms of the civil service.

The commission is made up of former permanent secretaries and experienced Whitehall figures. It previously included among its members Baroness Finn, who has since left to become Mr Johnson’s deputy chief of staff.

The recommendation to enable unelected representatives to become ministers was put forward by George Osborne, former Chancellor of the Exchequer, earlier this year.

In his evidence to the commission, Mr Osborne said he believed countries with presidential systems were better at bringing in outside talent to senior government roles and called for a system of non-parliamentary ministers to increase the talent pool.

He proposed establishing a new approach in which it becomes routine for senior business leaders to spend a four to five-year tour in public service, without the need to become a Parliamentarian for life.