Senior civil servants are concerned that Jeremy Corbyn lacks a firm grasp of both foreign affairs and the domestic agenda

Senior civil servants have become increasingly concerned about Jeremy Corbyn’s health and warned that he may be forced to stand down as Labour leader because he is not up to the job “physically or mentally”.

The future of Mr Corbyn, 70, was openly discussed at an event attended by mandarins this month amid suggestions that he has become “too frail and is losing his memory”.

They say they are increasingly worried about the prospect of him becoming prime minister because he is being “propped up” by his advisers and lacks a firm grasp of both foreign affairs and the domestic agenda.

One senior civil servant said: “When does someone say [he] is too ill to carry on as leader of the Labour Party let alone