Winds top 230 kilometres per hour
No reports of deaths
Hundreds of military personnel begin clean-up
Cyclone heading for Fiji
The Parliament building in the Pacific country of Tonga has been flattened after a powerful cyclone battered the main island, causing extensive damage.
With destructive winds of 230 kilometres per hour, category four Cyclone Gita ripped roofs from houses, brought down trees and caused widespread flooding.
Tens of thousands of people were left without power as the main island of Tongatapu experienced a complete blackout.
"It was a terrifying night," Graham Kenna from Tonga's National Emergency Management Office (NEMO) told the ABC's Pacific Beat program.
"I have been doing disaster responses for 30 years and I think it's the scariest night that I've had. It was horrific."
"We're on the third floor of one of the safest buildings in Nuku'alofa and the building was shaking and getting pounded by debris from missing roofs."
The Parliament building was more than 100 years old and it was not yet clear where the legislature would sit for now.
"It's an old building so there was always the possibility that that would occur," Tongan noble MP Lord Fusitu'a told the ABC.
"Successive legislatures over the years have suggested building a new parliament house and I guess that'll be a necessity now.
"It's a great disappointment."
Officials said the office of the weather bureau was also destroyed.
"The eye went over us, then we lost the meteorology office — it was blown away," Mr Kenna said.
"So we had not much contact as to where the cyclone was going."
There are so far no confirmed reports of deaths, but officials said at least three people were injured and up to 40 per cent of homes damaged.
Emergency authorities said about 70 per cent of the population had been affected and food and water would be a significant problem.
"Wind was blowing and we heard roofing torn and flying over, it was quite scary," NEMO director Leveni Aho told the ABC.
Australia's Department of Foreign Affairs said it was on standby to provide help, including military assistance and humanitarian supplies.
Hundreds of military personnel were clearing roads and disaster teams were already assessing the damage.
"We are sending teams to the field now, but it's still raining and still fairly windy," Mr Aho said.
"So it's going to be some time before we get a quick overview of the damages to the nation."
Weather experts say Gita shows no signs of abating as the storm continues to head towards Fiji's southern Lau islands.
It is expected intensify to a category five cyclone as it passes over the Ono-i-Lau group of islands.
- Australian Broadcasting Corporation
- © ABC