Christchurch port workers are planning strike action in a solidarity move with their Auckland comrades.
Unionised workers at Lyttelton Port are planning to boycott work on a docked ship but the move could be blocked by an emergency court hearing this morning.
Lyttelton Port of Christchurch chief executive Peter Davie told Radio New Zealand this morning that he understood more than 300 Maritime Union members were refusing to unload the container ship, Lisa Schulte, as it had been worked on by non-union staff at the Port of Auckland.
Mr Davie said: "We had discussions with unions ... about that and what action they may or may not take.
"We have to find a way through."
Mr Davie said he considered the action illegal and had already filed an Employment Court injunction to force staff back to work, following similar measures taken by port companies in Wellington and Tauranga.
The case was due to be heard in Christchurch today ahead of the ship's scheduled arrival at Lyttelton at 7.30pm this evening.