Port of Tauranga has put a full house sign up to any ships redirecting to it from Ports of Auckland because of an industrial dispute.
The Bay of Plenty port has already increased container volumes by 20 per cent in the six months to December from the same period a year ago, mostly because of new services it has attracted.
Chief executive Mark Cairns told NZ Newswire Port of Tauranga was almost at capacity.
"We're nudging the ceiling at the moment," he said.
"We're saying we can't handle any new ships wanting to redirect."
The Pacific International Lines ship Kota Permasan called at Tauranga rather than Auckland last weekend, with Ports of Auckland blaming union threats of a blacklist of vessels handled by non-unionised stevedores.
Mr Cairns said a number of vessels wanting to redirect had contacted Tauranga but he declined to say how many.
Three weeks of strike action began on Friday the Ports of Auckland in the latest twist in a five-month long dispute. The port wants to outsource jobs and the union says it wants to casualise them.
Maritime Union National President Garry Parsloe says the national conference of the Maritime Union of Australia has passed a resolution of support for Auckland workers and a donation was also made to Auckland workers.
The Auckland dispute was now on the global agenda for unions, he said.