The NBRU has hit out at the use of what it calls "scab labour"
The union representing Luas workers says that Transdev has behaved 'recklessly' in the ongoing row over pay hikes at the company.
It follows comments made by NBRU General Secretary Dermot O'Leary earlier who condemned the move by Luas operator Transdev to hire buses during a strike planned for St Patrick's Day.
The company will run shuttle services from Luas Park and Ride Stops into the city centre.
The NBRU has written to the Minister for Transport outlining their concerns over the latest development.
However, Transdev says it's important to have a service running for visitors to Dublin on our national holiday.
Talks at the Workplace Relations Commission (WRC) adjourned for the weekend last night and will resume on Monday.
SIPTU's Eoin Reidy says questions need to be asked about how Transdev run the company, saying "I think we're dealing with an employer who is quite reckless when dealing with the Luas":
Luas drivers have reduced their pay claim from 53% over five years, to between 27% and 30%. However, Transdev has refused to sit down with drivers, who make up 170 of the company's 250 staff.
The NBRU - which does not represent Luas workers - says it opposes the use of scab labour and that it has raised the concerns with the Minister for Transport.
The union's General Secretary Dermot O'Leary said the union has "written to the Minister questioning the actions of the Luas operator Transdev in engaging in what can only be described as strike breaking."
"Our members are extremely concerned that this use of scab labour to break a legitimate dispute may be replicated across the transport sector, at a time when ordinary decent bus and rail workers are seeking long overdue pay rises after eight years of pay cuts and Government imposed austerity measures."
Mr O'Leary says that while his members are in the tram drivers' corner, the union is also urging its members to take caution as "there are legalities involved here in terms of disputes. We're not directly involved in the dispute as a union":