Fijians living in low-lying areas were urged to flee to higher ground on Saturday as a cyclone bore down on the Pacific nation after leaving a trail of destruction in Samoa with up to 10 feared dead.
Cyclone Evan is intensifying and is expected to be packing winds of up to 230 kilometres an hour (143 miles per hour) by the time it slams into Fiji on Sunday afternoon.
Government officials feared it could be as devastating as Cyclone Kina which killed 23 people and left thousands homeless in 1993.
"I cannot stress enough how serious this is. Every Fijian will be affected but we must take preventative steps now," military leader Voreqe Bainimarama told the nation of about 900,000.
"Because this is the festive season I ask you to consider cancelling social events and to act responsibly, all of us need a clear mind for what is bearing down on us."
More than 60 evacuation centres have been set up in northern areas of Fiji and residents were being urged to move in before the storm hits.
"We are advising people to move to high ground, those who are living in lower-lying areas," Asesela Biuviti of the national disaster management office said.
"This is going to be an extremely bad cyclone to hit us and probably the worse that we've seen since Cyclone Kina," the permanent secretary for information, Sharon Smith-Johns, added.
Meanwhile, in Samoa the confirmed death toll from Evan rose to three with another seven people missing and feared dead after being swept away when the capital Apia's Vaisigano river burst its banks.
About 3,000 people remained in emergency shelters after their homes were either destroyed or left without essential services including power and water, the New Zealand High Commissioner in Samoa Nick Hurley said.
A clean up was under way with fallen trees and power poles removed to open main roads but progress was slow and it could be another two days before the full extent of the damage was known, he added.
There was no electricity on the main Samoan island Aporo, apart from private generators.
Both Australia and New Zealand responded to Samoan calls for help with Wellington sending a P3 Orion aircraft for aerial surveillance to assess the extent of the damage.
New Zealand Foreign Minister Murray McCully said an initial assessment showed "damage to outlying buildings, critical infrastructure and power lines, with flooding, many fallen trees and power outages".
McCully's counterpart in Canberra Bob Carr said Australian aid workers were already on the ground in Apia offering humanitarian assistance.
"We'll be consulting with the Samoan government today on how we can further assist with emergency relief," he said, adding that Australia was also on standby to help Fiji.