The Port of Tauranga has said its container terminal is running at 50% due to a Covid-19 scare caused by a visiting containership.

The New Zealand port said it would only be able to restore capacity when stevedores have been advised they can return to work after Covid-19 testing.

Officials sought urgent testing of workers who had been in contact with the 5,905-teu containership Rio de la Plata (built 2008), which had at least 11 positive cases on board.

The Singapore-flagged ship had arrived at Port of Tauranga on 4 August. The port operator was advised by Maritime New Zealand that the ship had been boarded two weeks earlier by an Australian pilot who had tested positive for Covid-19.

However, New Zealand maritime authorities subsequently cleared the ship for pilot boarding. The ship was also cleared to berth by local public health officials as part of the normal free pratique process.

The Port of Tauranga said a pilot boarded the vessel on Wednesday evening and brought the ship in to the Tauranga Container Terminal.

However, within hours New Zealand’s customs unexpectedly shut down operations on the ship and local public health officials advised the Port of Tauranga that its pilot and the stevedores unloading the ship should “go home and isolate while awaiting further instructions”.

Government agencies are later said to have “clarified the situation” and public health officials advised the port that operations could resume on the vessel and there was “no need for workers to isolate”.

“We have not received any official information from the ministry of health but have been advised informally that 109 negative tests have been received so far in this round of urgent testing,” the Port of Tauranga said.

“Our primary concern is for the port workers, including our pilots, who have been put in a very stressful situation.”

Almost all of the Port of Tauranga’s frontline staff are vaccinated, but it said there were “dozens of companies” that work in the port.

“Vaccinations have been available at Port of Tauranga since March but the order making vaccination compulsory was only introduced on 14 July,” the port said.

The Port of Tauranga said vaccinations were “another useful tool” in the fight against Covid-19, but it added that it would continue to follow the other precautions that have worked for the past 18 months including frequent cleaning, use of PPE, physical distancing from ship crews and regular Covid-19 testing.