Maritime NZ has closed its investigation into the death of a crewman on a container ship that was berthed at Bluff's South Port, after finding he died of natural causes.

The MSC Resilient III arrived at Port of Tauranga on January 1, and is due to leave for Tanjung Pelepas, Malaysia this morning according to the Port of Tauranga website.

Emergency services were alerted at 9.30am on December 21 to an incident on the MSC Resilient III vessel at the port in Bluff, where a person died suddenly.

South Port chief executive Nigel Gear says none of its staff or contractors were involved.

Cargo operations had finished. All the port employees and contractors had left the ship and the ship's crew were preparing the vessel for departure, Gear said.

Maritime NZ sent two of its investigators to Bluff.

The agency's principal advisor, Vince Cholewa, said the investigation was now closed.

'He died of natural causes and nothing untoward was found on the ship.”

A police spokesperson said the crewman's death had been referred to the coroner who would release their findings in due course.

Police were unable to say what the crewman's age and nationality was, or whether his body had been sent home.

Evan Harding/Stuff