The Maritime Union told the Ports of Auckland this week that it planned on extending the 235 member strike by 14 more days, to six weeks.
This follows the port's decision on Wednesday to make redundant almost 300 workers, including hundreds of strikers, and replace them with contractors.
The Union has made an application to the Employment Court, asking for a ruling on the port's decision.
A six-week consultation period for the redundancy process started yesterday.
Meanwhile, a rally against the redundancy of workers at the ports of Auckland will take place this afternoon.
The 4pm rally will feature speeches from port workers, community leaders and international union supporters, and will end with a 2km march to Teal Park in Mechanics Bay.
Firefighters, teachers and nurses' representatives will join the striking Auckland port workers in today's rally.
Union delegates from America and Australia were also expected at the rally.