The General Secretary of the National Bus and Rail Union has written to the head of the National Transport Authority to express 'disgust' at recent comments she made regarding absenteeism among bus drivers.

Appearing before the Oireachtas Transport Committee on Tuesday, NTA Chief Executive Anne Graham said that driver absences, even post Covid, were at a level that they did not feel was acceptable and that this was impacting services.

She was responding to concerns expressed by Social Democrats co-leader Catherine Murphy in relation to the reliability of bus services.

"Let me place on the record my absolute disgust at the audacity demonstrated by you in attacking bus drivers in such a manner," NBRU General Secretary Dermot O'Leary wrote in a letter to Ms Graham.

Mr O'Leary accused the NTA of showing nothing but disdain for public transport workers and of pointing the finger of blame for service problems at bus drivers.

He said that the authority had failed to express its appreciation to the men and women who had continued to provide bus services throughout the Covid-19 pandemic.

In his letter, Mr O'Leary asked if the NTA had considered the possibility that bus driver absenteeism might be linked to poor working conditions, long hours, a lack of toilet facilities and pressures to meet what he described as 'impossible' arrival and departure targets.