Health officials have confirmed two further Delta cases in Northland - while Tonga says it is no longer Covid-free after a passenger from a flight from Christchurch tested positive for the virus.

The Northland DHB advised the Ministry of Health this afternoon of two new community cases in Southern Kaipara.

The two cases are in the same household and at this stage have no known links to the current Northland cluster. Investigations are underway to determine connections to the current outbreak.

The pair were tested on 27 October and have been isolating with public health oversight.

Investigations are continuing to determine further details around their movements and to identify any locations of interest. A further update on will be provided tomorrow.

Meanwhile, One person has tested positive for Covid-19 in Tonga after arriving on a flight from Christchurch on Wednesday night.

Kaniva News reported that the case was confirmed by Tonga Ministry of Meteorology, Energy, Information, Disaster Management, Environment, Climate Change and Communications CEO Paula Ma'u.

This comes a day after Covid-19 Response Minister Chris Hipkins announced that one-way travel with Tonga and other "low-risk Pacific countries" like Samoa, Vanuatu and Tokelau will resume on November 8.

Hipkins said from November 8, low-risk travellers from Samoa, Tokelau, Vanuatu and Tonga would be able to bypass MIQ from November 8, in a one-way travel bubble arrangement.

However, the confirmation of the Tongan case has sparked concerns that the virus could have spread among the 215 passengers on board the flight who are now quarantined in Tongatapu.

According to Kaniva News, a senior doctor at Vaiola Hospital had sent an email out at 1.48pm today saying: "We have 1 positive case".

"No one allowed to go up to wards without 2 vaccinations except it is the patient. All attendances should have the 2 vaccinations and only 1 attendance per patient," the email said.

"Limit visits to only close family and 2 per visit. Need ID for visit up to ward. Above should start as soon as we can inform the public say start Nov 1 which is Monday next week."

This was the first case of Covid-19 in Tonga, and it is understood that the patient was in one of the MIQs in Nuku'alofa.

The Tongan case is believed to be linked to the two cases of Covid-19 reported in Christchurch on Thursday. Both cases lived together in the suburb of Bishopdale.

One of the cases had permission to go to Auckland to provide childcare and tested negative before returning to Christchurch.

The second case is a truck driver who completed deliveries around the Christchurch area and some trips to North Canterbury.

Both became unwell last week and were tested two days ago, but returned positive Covid tests on Wednesday night.

Ma'u said Tongan authorities had received the report of the Christchurch Covid-19 cases after the passengers arrived in Tonga.

"The passengers were being processed according to the normal procedure at the quarantine facilities and tested for Covid-19″.

The repatriated flight arrived with passengers including seasonal workers as well as some of Tonga's Olympic team officials who got stuck in New Zealand after the Olympic Games.

New Zealand's Ministry of Health said in a statement it was "investigating reports in Tongan media of a positive COVID-19 result from a person who boarded a commercial flight to Tonga from Christchurch on Wednesday.

"The case retuned a negative pre-departure test before leaving New Zealand. They are fully vaccinated with the Pfizer BioNTech vaccine and had their second dose on 15 October.

"They were tested in routine Day 0 testing yesterday and returned a positive result today.

"The Ministry, along with the Ministry of Foreign Affairs and Trade, is working with officials in Tonga to confirm the case. There will be further updates on this tomorrow."