The head of Lyttelton Port doesn't expect any disruption to its operations from industrial action starting this Friday.
The Rail and Maritime Union says the partial strike by logistics officers over a pay dispute will have a major impact on the port.
But the port's chief executive, Peter Davie, says the action will only affect one of three daily shifts, and he expects work to continue as normal.
Mr Davie says he is surprised and disappointed the union has chosen to take the strike action.
The Rail and Maritime Transport Union South Island organiser, John Kerr, says the failure of mediation today with the Lyttelton Port Company management means that industrial action is imminent at the port.
Mr Kerr says its members have been negotiating for a pay increase since before Christmas.
He says from Friday they will take industrial action that will result in delays and backlogs building up at the port.
He says its members are claiming a 4 percent increase over 12 months, while management have offered 2.85 percent.
