The Ministry of Primary Industries has confirmed it does not intend to prosecute the owners of a ship evicted from New Zealand because it was severely contaminated.
MPI ordered the palm kernel bulk carrier, DL Marigold, to leave within 24 hours on Sunday after it arrived in Tauranga from Indonesia.
Divers found dense clusters of barnacles and tube worms on the vessel's hull.
• Dirty ship oredered to leave Tauranga
Sharon Tohovaka, Ministry of Primary Industry's border clearance capability manager, said the DL Marigold was identified as a risk before it arrived in Tauranga.
The ship's departure from New Zealand waters was a "precautionary" biosecurity measure.
Ms Tohovaka said no other vessels had been affected, and while there was a potential for contamination of local waters, there was no evidence this had happened.
MPI would not be prosecuting the owners, but the vessel would not be permitted to return to New Zealand until it was cleaned and met biosecurity requirements, she said.
Reon Tuanau, Ngai Te Rangi Iwi's resource management unit manager, said he was stunned to learn of the eviction from a media report, rather than from MPI.
"Good on MPI for acting so quickly but we don't know what sort of fouling or other nasties this ship has left in our harbour."
It was crucial Tauranga iwi were notified of any potential risks from invasive marine species, and he planned to take the matter up with the Ministry.
A Ministry spokesperson said it was not usual practice to inform local iwi of day-to-day decisions by border officials, but the Ministry would be happy to keep them informed of similar decisions in the future.
Port of Tauranga's operations manager Phil Julian said the Port would be writing to the ship's owners asking for an explanation.
Mr Julian said the matter would also be brought to the attention of other importer and exporter groups to reinforce the Port's expectations about the cleanliness of their vessels.
Emma-Leigh Hodge, Green Party spokeswoman for Tauranga, said MPI should be congratulated for acting so quickly.
The evicted vessel had been intending to head to Fiji to be cleaned, but was refused entry.
Facts about tube worms
* It is a worm-like invertebrate which anchors its tail to an underwater surface.
* It secrets a mineral tube around its body.
* They're an aggressive species which can easily dominate native fauna and have dramatic effects on the environment eco-system in an area.