It is not known which plants will be affected by the redundancies
There are renewed fears over the future of jobs at the Monkstown Nortel plant.
Administrators for the group have confirmed there will be another wave of job losses, but did not say which plants were to be affected.
The UK arm of the multi-national telecommunications giant went into administration earlier this year.
In March, 87 workers at the Monkstown factory were made redundant, leaving a core workforce of 400. Since then there has been a continued fall in revenue.
The administrators, Ernst and Young, have not given details of the numbers involved.
Nortel also has factories in Maidenhead and Harlow.
The trade union Unite is planning to protest outside the Monkstown plant on Friday.