The National Bus and Rail Union is threatening to take industrial action unless the school bus fleet is urgently upgraded.
The NBRU's warning comes following another incident involving a Bus Éireann school bus in Co Westmeath earlier today.
The bus was taken out of service after the driver detected smoke coming from the brakes.
The union says it is inevitable there will be further incidents with the current fleet given the majority of school buses in use that have clocked up hundreds of thousands of miles.
