Three people have been killed after the violent eruptions of the Hunga Tonga-Hunga Ha'apai volcano and consequential tsunami hit Tonga, said the government's first official update following the "unprecedented disaster."

The evacuation of some outlying islands had begun after the destruction of homes. Internet is still down and domestic calls remain limited in the country, read a government statement.

In the statement, the prime minister's office confirmed the deaths of a 65-year-old woman on Mango Island and a 49-year-old man on Nomuka Island, in addition to a British national.

A number of injuries were also reported.

On Tuesday afternoon, two New Zealand naval ships carrying fresh water, emergency supplies and diving teams were being sent to Tonga to provide support.

On Friday and Saturday, the Hunga Tonga-Hunga Ha'apai volcano erupted violently and triggered tsunami in Tonga.

The Hunga Tonga-Hunga Ha'apai volcano is part of the highly active Tonga-Kermadec Islands volcanic arc, a subduction zone extending from New Zealand north-northeast to Fiji. Over the past decades, the volcano has erupted several times. 

(With input from agencies)