The New Zealand Government has pledged $500,000 to the Island of Tonga. The offer for a reconnaissance flight, and an Orion will take off tomorrow morning provided conditions allow, has been accepted by the Government of Tonga.

At present ash has been spotted at 63,000 feet.

In a press conference today, New Zealand Prime Minister Jacinda Ardern says the Australian Government are also on standby to lend assistance required for Tonga.

Radio New Zealand reports that a naval vessel has also been put on standby to assist if necessary.

"[There is] an urgency here.

“We want to make sure we're on the ground as soon as possible, but for our Navy vessels it will take several days to reach Tonga, and we need to finely balance the need to get there quickly but to make sure we also get the people and resources they need there as well and in some cases, we have parts of Tonga where we just haven't been able to establish communication."

Ardern has also been in touch with Australia's Prime Minister Scott Morrison so that both governments can work in tandem in their response.

She said a priority is the supply of water for Tonga.

The reconnaisance flight will be useful to see the impact of the volcanic eruption on the low-lying islands, Ardern said.

"At the moment we stand ready to assist," Ardern said, but she added that the conditions at the moment do not make it a stable environment for aircraft to operate in.

That is why naval vessels may be needed to head to the region.

"We are preparing for those ships to sail as we speak."

The Canterbury could be deployed within eight hours, she said.

Defence Force Minister Peeni Henare said it's not known yet what has 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."

Water would be one of the critical things that New Zealand could help with, he said.

Medics, logistics staff and engineers will be the most needed job skills for staff deployed to help out, he said.