Luas drivers have announced six more days of industrial action next month.
The strikes will be for four hours each day, on Thursday 2 and Friday 3, then during the 7, 8, 9 and 10 of June.
It is in addition to four more strike days this month, in a dispute over pay.
Luas operator Transdev stands to lose 100,000 euro every day the drivers strike, and management at the company insists that the 23 percent pay claim sought by the workers is 'unaffordable'.
Luas drivers, who are represented by SIPTU, have vowed to push on with their pay claim - despite Transdev implementing a 10% pay cut as the drivers continue to strike.
Siptu's transport spokesperson John Murphy says this is an escalation of the dispute: “We have issued six dates for early June and these are going to consist of four hour stoppages,on each of those six dates.”
Meanwhile Transdev who operate the Luas has said it will now consult with its lawyers and respond to workers in the coming days.
The company said this latest notice of strike action is designed to cause maximum to disruption to Luas customers, with minimum loss of pay to the drivers.
They also said the four hour stoppages will in effect disrupt the Luas for 6 and a half hours, as the trams will need to be stood down and recommissioned.
Transdev says the dispute is putting the company in a very challenging financial position.