The Labour Relations Commission (LRC) is expected to contact management at Bus Éireann and trade unions at the company today in an attempt to avert a threatened strike by school bus drivers on Friday.
It is understood that the parties are considering proposals put forward by the LRC. However, no agreement had been reached by last night after several hours of talks.
The strike action, which could affect more than 14,000 school children, was deferred last Friday for a week to allow for further talks between the parties.
The row concerns pay levels for part-time school bus drivers.
Siptu is seeking parity with full-time Bus Éireann drivers.
The National Bus and Rail Union wants a "substantial increase" for its part-time drivers.
Bus Éireann has argued that the Siptu claims have been rejected by the Labour Court and a rights commissioner.
A spokeswoman for the company said last night that discussions were at a delicate stage but it was hoped that a strike could be averted if all parties were reasonable.
Siptu said last night that the industrial action would go ahead on Friday if no resolution was found today.
Siptu has said that the drivers earn €11.66 an hour and have no overtime rates, pension, sick pay or other benefits.
It said that they were "amongst the lowest-paid workers in the public transport or education sectors".
Bus Éireann employs about 550 drivers providing school bus services around the country.
Meanwhile, the process chaired by the National Implementation Body (NIB) aimed at preventing a dispute at Aer Lingus over a €20 million cost-cutting plan is to continue.
The process, involving the Labour Relations Commission and outside consultants Grant Thornton, was put in place last month by the NIB in an attempt to avert a strike by Siptu.
In a statement yesterday, the NIB, which is the main trouble-shooting body under social partnership, said it had met management at Aer Lingus and trade union representatives on Monday night.
"The body also met with the Labour Relations Commission and Grant Thornton representatives and, having considered their report on the process to date, the body recommended that the current intensive process should continue and agreed to monitor progress over the coming days."