John Corrigan, the chief executive of the National Treasury Management Agency (NTMA), is under severe time pressure to restock AIB's board after the resignations of its chairman, managing director and two non-execs in the last 10 days.

Corrigan, who is heading the search for the new AIB directors, was in London last week to meet headhunters and potential candidates, amid concern in the banking sector that a proper search was impossible under the time constraints.

Chairman Dan O'Connor and managing director Colm Doherty were forced out in September after the government admitted AIB needed another €3bn in capital and would be effectively nationalised. Directors Robert Wilmers, chief of M&T Bank, and Kieran Crowley followed days later.

It is understood other directors have been asked to postpone their resignations for the sake of board stability.

Senior regulators are pushing for a major board clear-out at AIB by the end of the year, after risk management and governance reviews are carried out by third-party consultants.

Finance minister Brian Lenihan wanted O'Connor, a former GE executive, to run the bank last year to avoid appointing the controversial Doherty to the top job after a fruitless six-month search.