Communication links with the island kingdom of Tonga, in the South Pacific, were still limited on Sunday following an underwater volcanic eruption.
The giant eruption of the Hunga-Tonga-Hunga-Ha'apai volcano on Saturday evening had triggered a tsunami and blanketed Tonga in volcanic dust, New Zealand Prime Minister Jacinda Ardern said.
The "significant eruption" had severed communication links, but as yet there were no official reports of injuries or deaths, Ardern said.
She said communication was still "very limited" with the undersea cable impacted, possibly due to power cuts. Authorities were working to urgently restore communications, Ardern said. Local mobile phones were reportedly working.
"At the moment we are mainly receiving information from our High Commission ...unfortunately from the outer islands we don't have a lot of information," Ardern said.
Authorities in Tonga had advised Ardern a tsunami had "significantly impacted" the northern side of Nuku'alofa, with boats and boulders washed ashore and buildings damaged.
The New Zealand Defence Force would deploy a surveillance flight on Monday subject to conditions in the area, Ardern said.
"Unfortunately at the moment it is not a stable environment for aircraft to operate in."
Ash had been spotted at 63,000 feet, making it unsafe to fly, Ardern said.
A naval vessel has also been put on standby to assist if necessary.
Minister of Civil Defence Peeni Henare said it was not known yet what had happened under the water.
A New Zealand hydrographic vessel may be able to head to Tonga.
"Our people are ready to deploy. We just have to make sure they are fitted out with what the Tongan people need," Henare said.
Ardern said a priority was the supply of water for Tonga.
Fiji MetService said ash was falling over parts of Fiji, about 600 kilometres away from the volcano.
It warned people to protect water supplies, stay indoors and wear a mask if heading outside.
Tsunami waves were reported across the globe, including in New Zealand where a number of boats at a Northland marina had sunk following a 1.3 metre tsunami.
Flooding in Santa Cruz, California, was also attributed to the eruption. Japan recorded a 1.2 metre tsunami in the city of Amami, the Kyodo News Agency reported.
Japan lifted tsunami warnings for its entire coast around noon, while warnings that had applied to much of Australia's south-east coast were downgraded Sunday afternoon. Marine warnings remained in place for the New South Wales coast and two offshore islands.
Save The Children Fiji chief executive Shairana Ali said tidal and tsunami waves had been hitting Fiji and Vanuatu.
There had been damage to coastal areas but no fatalities, Ali said in a statement.
The pressure surge from the eruption was recorded across the world, including some 16,000 kilometres away in Britain, the Met Office said.
Local media in Tonga reported a downpour of ash, the flooding of properties and disruptions to phone and power connections before communication links went down.
The Bureau of Meteorology Australia said a 1.2 metre tsunami wave had been observed at Nuku'alofa, Tonga's capital on Saturday.
UN Secretary General Antonio Guterres said in a statement he was deeply concerned by reports of a tsunami and ash affecting Tonga and that United Nations offices in the Pacific are closely monitoring and on standby to provide support.
