Ongoing union action will halt overnight operations at the Port of Lyttelton for a fifth weekend in a row.
A ban on overtime by maintenance staff has been in place since mid-December while the Rail and Maritime Transport Union fights for a pay increase of between 3 and 4 percent.
The port and the union met for mediation talks on Wednesday and while both parties say they are making progress, there has been no resolution.
A union organiser, John Kerr, said the overtime ban was still in place this weekend but talks with the port would continue next week.
"We're having outlying meetings if you like to work on specific issues to do with negotiations and then the full team will come back together next Wednesday with a mediator from the Ministry of Business, Innovation and Employment."
Mr Kerr said the union was optimistic about resolving the dispute.