Cyclone Waka ripped apart homes and left palm trees like broken matchsticks dotting the hills of the northern Tongan islands of Vava'u, but resilient locals are already putting the devastation behind them.

The cyclone that swept through the island group a week ago has been described by Tongans caught in the storm as the worst to strike the tiny Pacific nation.

The first secretary at NZ's High Commission, Brian Chambers, spent the weekend inspecting badly affected areas.

He said the devastation was widespread across the main island and into smaller surrounding islands.

"Trees have been uprooted, broken off at the trunks, and banana palms are lying all over the ground.

"Everything is pretty brown when it is usually lush and green at this time of year," he said.

Elderly Tongan villagers had told Mr Chambers that the cyclone, which brought winds of 135 knots during the eye of the storm, was the worst they had experienced.

"The wind speed may not seem like a lot but the buildings are pretty flimsy here. They are not built to withstand these weather conditions."

Mr Chambers said that at least 90 per cent of power lines were on the ground or tangled up in trees and the poles which supported them had been snapped off at the base.

Some power has been restored to Government buildings and businesses in Neiafu, but it is expected to be some time before residents have their supplies back.

A big concern is contaminated water supplies as household tanks are filled with dirt, leaves and branches.

Mr Chambers said islanders would also need extra food supplies in the next few weeks as the root crop of taro and kumara had been destroyed.

He said the rain belt that followed cyclones was much shorter than the 3 to 4 days usually experienced so people had been able to sleep outside under corrugated iron.

"The people are pretty resilient. They are already out reconstructing their housing, putting roofing iron back on and hanging out their clothes to dry."

The Red Cross had acted quickly after the disaster, bringing in tarpaulins, lanterns and cookers.

An Australian C130 Hercules aircraft had also dropped off 650 tarpaulins, 50 marquee tents, 100 camping tents, water purification tablets, blankets and other emergency supplies.

Mr Chambers said New Zealand expected to get some idea today from the Tongan Government of what it could do to help with the recovery effort.

The Ministry of Foreign Affairs and Trade said the assistance package was likely to focus on Tonga's long-term needs.