9.45am update: New Zealand's National Emergency Management Agency – NEMA has extended the warning to stay off NZ beaches and shore areas to also include the west coast of the South Island.

'We expect New Zealand coastal areas on the north and east coast of the North Island, the west coast of the South Island and the Chatham Islands to experience strong and unusual currents and unpredictable surges at the shore following a large volcanic eruption at Hunga-Tonga-Hunga-Ha'pai in Tonga,” says a NEMA spokesperson.

'Strong currents and surges can injure and drown people. There is a danger to swimmers, surfers, people fishing, small boats and anyone in or near the water close to shore.

'People in or near the sea should move out of the water, off beaches and shore areas and away from harbours, rivers and estuaries until this Advisory is cancelled.”

NEMA says there is no need to evacuate other areas unless directly advised by local civil defence authorities. Coastal inundation - flooding of land areas near the shore - is not expected as a result of this event.

'We are advising people to move out of the water, off beaches and shore areas and away from harbours, rivers and estuaries,' says a NEMA spokesperson.

'Do not go to the coast to watch the unusual wave activity as there may be dangerous and unpredictable surges.

'Listen to local civil defence authorities and follow any instructions. Share this information with family, neighbours and friends.”

Strong and unusual currents and unpredictable surges have been observed on tsunami gauges and the threat must be regarded as real until this Advisory is cancelled.

This National Advisory has been issued following advice from GNS Science.

'This is the largest eruption from Hunga-Tonga-Hunga-Ha'pai Volcano so far, and the eruption is ongoing.”

The situation may change as new information becomes available. Listen to the radio or TV for updates, or check www.civildefence.govt.nz

Earlier, 7.45am:

New Zealand's National Emergency Management Agency – NEMA - is advising New Zealanders to stay off the beaches and shore areas on Sunday.

The agency is expecting NZ coastal areas on the north and east coast of the North Island and the Chatham Islands will experience strong and unusual currents and unpredictable surges at the shore following a large volcanic eruption at Hunga-Tonga-Hunga-Ha'pai in Tonga.

'Strong currents and surges can injure and drown people. There is a danger to swimmers, surfers, people fishing, small boats and anyone in or near the water close to shore,” says a NEMA spokesperson.

'People in or near the sea should move out of the water, off beaches and shore areas and away from harbours, rivers and estuaries until this Advisory is cancelled.”

Papamoa resident Janine Bjerring went for an early morning walk with her dog along Papamoa beach only to unexpectedly find sea foam and waves sweeping up into the plantings in the sand dunes.

"I didn't know what had happened in Tonga and that we were advised to stay off the beaches until after we were back home,' says Janine, who took some photos before leaving the beach.

NEMA is advising people to not travel to the coast to watch the unusual wave activity as there may be dangerous and unpredictable surges.

Papamoa beach early on Sunday morning. Photo: Janine Bjerring.

NEMA says there is no need to evacuate other areas unless directly advised by local civil defence authorities. Coastal inundation- or flooding of land areas near the shore - is not expected as a result of this event.

'We are advising people to move out of the water, off beaches and shore areas and away from harbours, rivers and estuaries,” says a NEMA spokesperson.

'Do not go to the coast to watch the unusual wave activity as there may be dangerous and unpredictable surges.

'Listen to local civil defence authorities and follow any instructions. Share this information with family, neighbours and friends.”

Strong and unusual currents and unpredictable surges have been observed on tsunami gauges and the threat must be regarded as real until this Advisory is cancelled.

This National Advisory has been issued following advice from GNS Science.

'This is the largest eruption from Hunga-Tonga-Hunga-Ha'pai Volcano so far, and the eruption is ongoing.”

The situation may change as new information becomes available. Listen to the radio or TV for updates, or check www.civildefence.govt.nz