There is significant damage to the western coast of Tonga's main island of Tongatapu.
The New Zealand High Commission says the damage is centred along the western coast, where there are many resorts, and the waterfront of the capital, Nuku'alofa.
A thick layer of ash remains blanketed over the capital.
Authorities are working to establish communication with smaller islands "as a matter of priority", the commission said.
The commission advised any New Zealanders in Tonga to register with www.safetravel.govt.nz and urged them to follow advice from local authorities, including any tsunami evacuation orders.
The Defence Force carried out a surveillance flight of the islands today. Plans are underway for a humanitarian relief flight when conditions allow.
RNZ
