Purcell demanded more staff and promotions

It can also be revealed that Department of Justice staff who worked outside office hours and travelled abroad during Ireland's Presidency of the European Union received one-off bonus payments.

After receiving the bonuses, senior officials then requested additional payments for staff who did not travel abroad but worked extra hours during the presidency.

In January 2014, Mr Purcell wrote to Department of Public Expenditure and Reform secretary general Robert Watt warning staff morale had hit an all-time low.

"The loyalty, commitment and dedication to strong work that was manifested during the presidency cannot be taken for granted, however, and indeed has largely worn thin," he said.

"My meetings with staff inform me that there is growing resentment and frustration at being taken for granted and undervalued."

He said there was an "urgent need" for promotions to retain "loyalty, enthusiasm and commitment".

He also noted other departments were permitted to breach the recruitment moratorium introduced in 2010.

On taking over from Alan Shatter as Justice Minister, Frances Fitzgerald wrote to Public Expenditure and Reform Minister Howlin raising concerns about the loss of senior staff. Ms Fitzgerald said management were battling to ensure there was enough senior staff to "keep the lights on".

The main focus of her concern was the numbers of principal officers retiring.