Technicians are striking over pay
More than 150 staff at telecommunications company Nortel are staging a half-day strike at the County Antrim factory in a dispute over wages.
Technicians at the plant in Monkstown are taking the action after pay talks with management collapsed.
Unite union spokesman Terry Collins said the half-day strikes would continue every Monday until the situation was resolved.
"It is time our members were paid back for all their efforts," he said.
"We have been working closely with the company over the past 18 months on 'lean manufacturing' and have made £3m in savings at the Monkstown plant. "