This move has caused frustration among partners and staff over possible delays or the collapse of the deal, with some saying the firm is in a chaotic state with signs of “low morale” and “infighting”.

The big four firm’s global chair and CEO, Carmine Di Sibio, sought to reassure staff that the separation of the businesses would go ahead, but some current and former EY partners and staff have called for Mr Di Sibio and other senior leaders who masterminded the break-up plan to leave if they cannot make it happen, the Financial Times reports.

To make the deal happen, Mr Di Sibio must persuade EY’s 13,000 partners to agree on the proposal. In a Thursday message Mr Di Sibio claims to have “made significant progress on many aspects of this transaction and now focused on resolving a few remaining issues so that we can move forward”.

Without naming EY, rival big four firm Deloitte’s global boss, Joe Ucuzoglu, commented on the breakup plans in a 20-minute video sent to partners on Thursday in which he criticised the strategy and said his firm would not follow suit.