A C-130 Hercules military transport plane left New Zealand carrying water containers, kits for temporary shelters, generators, hygiene supplies and communications equipment, New Zealand's Foreign Minister Nanaia Mahuta said.

Australia was also preparing to send two C-17 Globemaster transport planes with humanitarian supplies. The flights were all due to arrive in Tonga on Thursday afternoon.

The deliveries will be done with no contact because Tonga is desperate to make sure foreigners don't bring in the coronavirus. It has not had any outbreaks of Covid-19 and has reported just a single case since the pandemic began.

"The aircraft is expected to be on the ground for up to 90 minutes before returning to New Zealand," Defense Minister Peeni Henare said.

UN humanitarian officials report that about 84,000 people — more than 80 per cent of Tonga's population — have been impacted by the volcano's eruption, U.N. spokesman Stéphane Dujarric said, pointing to three deaths, injuries, loss of homes and polluted water.

Communications with Tonga remain limited after Saturday's eruption and tsunami appeared to have broken the single fiber-optic cable that connects Tonga with the rest of the world. That means most people haven't been able to use the internet or make phone calls abroad, although some local phone networks are still working.?

A navy patrol ship from New Zealand is also expected to arrive later Thursday. It is carrying hydrographic equipment and divers, and also has a helicopter to assist with delivering supplies.

Officials said the ship's first task would be to check shipping channels and the structural integrity of the wharf in the capital, Nuku'alofa, following the eruption and tsunami.?

Another New Zealand navy ship carrying 250,000 litres of water is on its way. The ship can also produce tens of thousands of litres of fresh water each day using a desalination plant.

Three of Tonga's smaller islands suffered serious damage from tsunami waves, officials and the Red Cross said.?

The U.N.'s Dujarric said "all houses have apparently been destroyed on the island of Mango and only two houses remain on Fonoifua island, with extensive damage reported on Nomuka". He said evacuations are underway for people from the islands.?

According to Tongan census figures, Mango is home to 36 people, Fonoifua is home to 69 people, and Nomuka to 239. The majority of Tongans live on the main island of Tongatapu, where about 50 homes were destroyed.?

Dujarric said the most pressing humanitarian needs are safe water, food and non-food items, and top priorities are reestablishing communication services including for international calls and the internet.

Tonga has so far avoided the widespread devastation that many initially feared.