Tonga eruption and tsunami: Jacinda Ardern shares heartwarming message from Tonga PM Siaosi Sovaleni following disaster

Jacinda Ardern has shared a snippet of her conversation with the Prime Minister of Tonga almost a week after an underwater volcano violently erupted, blanketing the kingdom in ash, contaminating drinking water and severing communication lines, while a devastating tsunami decimated isolated island communities.

Three fatalities have been confirmed following the explosion of Hunga Tonga-Hunga Ha'apai on Saturday - two Tongan nationals, a 65-year-old woman in Mango and a 49-year-old man in Nomuka, and one foreign national, 50-year-old British woman and animal rescuer, Angela Glover.

New Zealand has been actively supporting Tonga and its recovery in the aftermath of the explosion, with the Government committing $1 million in humanitarian assistance. Naval vessels were deployed to the Pacific kingdom earlier this week carrying personnel and much-needed supplies, while a Royal New Zealand Air Force C-130 Hercules arrived in Tonga on Thursday with water containers, temporary shelters, power generators, hygiene kits, and communications equipment. The HMNZS Aotearoa, carrying 250,000 litres of water and a desalination plant able to produce 70,000 litres per day, is expected to arrive in Tonga on Friday.

Infrastructure has been significantly damaged, with the strength of the blast severing Tonga's sole subsea communications cable and cutting off the kingdom from the wider world. On Wednesday, it was confirmed that telephone links had been largely reconnected - however, restoring full internet connectivity is likely to take a month or more, according to the owner of the cable.

With international calls now back on the cards, Prime Minister Jacinda Ardern was able to contact Tonga's Prime Minister, Siaosi 'Ofakivahafolau Sovaleni, on Thursday evening to get an update on the archipelago's situation.

In a post to her social media platforms on Friday afternoon, Ardern shared a snippet of their conversation

"Last evening I had a chance to speak with Prime Minister Sovaleni of Tonga. As we spoke he described to me that they could see the HMNZS Wellington pulling into port. It was such a relief to know that our first navy vessel had arrived to support relief efforts," Ardern captioned the brief clip.

"We spoke a lot about the communication issues, and I shared all the love and concern people had conveyed to Tonga over the past days. But rather than pass on a message, I asked if there was anything the Prime Minister wished to share directly with the Tongan community here in New Zealand, which I could record on my phone. This is what he had to say."

The Prime Minister then provided a translation of Prime Minister Sovaleni's message: "I praise God for his mercy and for keeping us safe so that we are able to be here on this blessed day. I thank you all for your prayers during this challenging time. I hope you will be able to connect with your own families and friends in the near future.

"Lots of love, Hu’akavameiliku."

More ships and aircraft carrying humanitarian aid are due to arrive in Tonga over the coming days as the international community responds to the nation's calls for urgent assistance.

United Nations spokesperson Stéphane Dujarric said in a briefing that the agency is in close contact with local authorities.

"Assessment teams have reached most parts of the country, including remote and isolated islands," Dujarric said.

"We remain seriously concerned about access to safe water for 50,000 people throughout the country. Water quality testing continues, and most people are relying on bottled water."

Some 60,000 people have been affected by damage to crops, livestock and fisheries due to ashfall, saltwater intrusion and the potential for acid rain, Dujarric said. There are also reports of fuel shortages.

Australia's foreign minister Marise Payne said on Friday that cash donations to Tonga for immediate humanitarian supplies - Australia has already donated $1 million - would need to be followed with more substantial support for rebuilding.

"The impact of this volcanic eruption and the subsequent tsunami and the damage the inundation is causing will be an ongoing challenge for Tonga, particularly in relation to infrastructure," she told Australian radio, adding that New Zealand and Fiji were also working closely with Tonga.

Tongans have since turned to social media to share images of the tsunami's destruction and tell their stories of the devastating eruption.

NASA's Goddard Space Flight Center said the force of the eruption was estimated to be the equivalent of five to 10 megatons of TNT - or more than 500 times that of the nuclear bomb the US dropped on the Japanese city of Hiroshima at the end of World War Two.