An all-out strike by Luas drivers looks more likely after talks between management and SIPTU failed to resolve the deadlock today.
SIPTU says the Luas operator Transdev warned it may put staff on protective notice, if the dispute continues.
Siptu's Transport official John Murphy says workers were also told today temporary lay offs could be on the cards
In a statement issued after today's meeting, Transdev said there is no basis for more talks or other intervention in the dispute.
Transdev says the union's expectations remain in excess of what was proposed at the WRC and subsequently rejected by drivers.
It says it wanted to share the financial challenges the company is facing after the five days of strike action since the WRC proposal was rejected.