CEANN Comhairle John O'Donoghue has more than three times the amount of staff at his office than his predecessor, an increase that has trebled staff costs to nearly half-a-million euro annually, the Sunday Tribune has learned.

In the previous Dáil, Ceann Comhairle Rory O'Hanlon had just three staff at his disposal – a private secretary, a secretarial assistant and a clerical officer – whose combined salaries cost an estimated €141,717.

O'Donoghue's term in office, which began in 2007, has seen that number increase to 10, with a staff bill increasing to €470,095, according to figures obtained under the Freedom of Information Act.

This includes an estimated salary of €107,791 for special adviser Dan Collins – that figure arrived at by Oireachtas officials as the midpoint on the pay scale.

In addition to Collins, a private secretary, personal assistant, two junior clerks, a staff officer, a secretarial assistant and three clerical officers all report directly to John O'Donoghue.

It is the latest in a series of revelations for the Ceann Comhairle who, as Minister for Arts, Sports and Tourism, ran up bills totalling some €550,000 during his five years in that office.

During his first three-and-a-half years in office O'Donoghue accumulated €350,000 in travel expenses for himself and his wife Kate-Ann.

After eight weeks of Sunday Tribune revelations, O'Donoghue finally came out last week and apologised.

In a second letter to his Dáil colleagues he wrote: "I sincerely regret that I did not pay more attention to the cost of the arrangements provided for me.

"I was fully focused on my duties as an office holder at the time and would not be concerned with this level of detail. I am sorry that these costs occurred."

A statement from the Houses of the Oireachtas Communications Unit sought to downplay the current level of staffing at the Ceann Comhairle's office, saying that it was not within his control.

It said that staff numbers were based on the findings of the International Benchmarking Review (IBR) which was conducted a number of years ago before the Houses of the Oireachtas Commission was set up in 2004.

"The IBR set down a marker that a future office holder may require resources in line with that of a minister," it said. "The Ceann Comhairle does not have the authority to decide staffing levels in his office. Staffing levels of all office holders within the Houses of the Oireachtas, including that of the Ceann Comhairle, are agreed by the Houses of the Oireachtas Commission. Staff numbers in the Ceann Comhairle's office are broadly in line with those in a minister or minister of state's office."