Fiji on Thursday declared a 30-day state of natural disaster as the category 5 tropical cyclone Yasa hit the island country.

While making the announcement, Fiji's Director for National Disaster Management Office (NDMO) Vasiti Soko said that developments may lead to additional regulations, reports Xinhua news agency.

A curfew between 4 p.m. on Thursday and 4 a.m. on Friday bans people's outdoor movements unless necessary, she said, adding that people in emergency situations should contact the police and military personnel for assistance.

Prime Minister Voreqe Bainimarama on Thursday urged Fijians to prepare for the worst as the Yasa could cause devastation worse than tropical cyclone Winson in 2016, which killed 44 people and caused extensive damage to the nation.

He warned that more than 850,000 Fijians or 95 per cent of the total population is set to be affected by Yasa.

According to the Nadi Weather Office on Thursday, the centre of tropical cyclone Yasa is currently at the edge of Vanua Levu, Fiji's second largest island, and the cyclone is expected to cross the northern part of the country in a couple of hours.

Close to its centre, cyclone Yasa is expected to have very destructive winds at speed up to 240 km per hour with momentary gusts up to 345 km per hour.

According to local media reports, cyclone Yasa has caused damages to houses and landslides across the country.

In Viti Levu, Fiji's main island where the capital Suva is located, an unplanned power outage occurred on Thursday with the time for power restoration remains unknown.

Hundreds of Fijians have moved into evacuation centres set up by the Fijian government in response to the tropical cyclone.

Schools remained closed on Thursday while all public transport services and sea services ceased.

The tropical cyclone season in the South Pacific region runs between November and April every year and Fiji is expected to experience up to three tropical cyclones during the current season.