Siptu members at Brinks have voted by two to one to reject the settlement proposals put forward from yesterday's talks at the Labour Relations Commission.
The number of ATMs affected by industrial action at security firm Brinks Allied could reach close to 300 in the coming days, the Irish Payment Services Organisation (IPSO) says.
Their warning comes after Siptu members at Brinks today voted by two to one to reject the settlement proposals which emerged from yesterday's talks at the Labour Relations Commission.
The dispute over is over an attempt by the company to introduce new security procedures that employees claim would leave them more vulnerable to "injury or even death". They also claim newly introduced security vehicles are less safe than their old ones.
The most controversial element is an instruction to van-drivers to drive away from a threatened colleague in the event of a robbery.
Around 200 ATMs went unserviced over the bank holiday weekend because workers refused to operate the new procedures and IPSO this evening warned that a further 80 machines could be affected.
The dispute has affected non-branch cash machines owned by AIB, Bank of Ireland and Ulster Bank many of which are now out of cash and branch-based ATMs are likely to be affected in days.
The banks were not prepared to comment this afternoon on what would happen if the matter is not resolved quickly.
Ms Úna Dillon, manager IPSO card services said customers in affected areas should consider other ways of accessing cash.
"In addition, many supermarkets, convenience stores and forecourts now have in-store ATMs that can be used." She also advised Laser card holders to use their cashback option at retail outlets and reminded the public that services such as checking account balances and paying bills can also be done online.
Both sides have now agreed to seek an early hearing at the Labour Court to find a resolution.