WELLINGTON (AFP) - Tropical Cyclone Sarai was bearing down off the coast of Fiji on Friday (Dec 27), with the archipelago's disaster agency warning some residents to move to higher ground ahead of possible flooding.

The Fiji Meteorological Service warned of "damaging gale force winds" and heavy rain with coastal flooding expected in some areas as the cyclone intensifies.

Sarai is expected to be a Category Two storm by the time it passes near the main island of Viti Levu early on Saturday, with average winds of 65kmh and gusts of 90kmh.

Dozens of people were been evacuated in the country's second city Lautoka and on the small island of Ovalau, as flash flood warnings were issued.

The Fiji Disaster Management Office had activated its emergency shelters and issued a public advisory for people to have their "disaster kits" ready.

"Sixty-three people are now taking shelter in three evacuation centres around the country," the National Disaster Management Office said.

Meanwhile, the plans of thousands of tourists who flock to the South Pacific island nation over the Christmas-New Year holiday period were upended as flights were cancelled or delayed.

Many day cruises around the islands have been called off while Fiji Airways cancelled several inter-island flights and flights to Australia and New Zealand.

Flights to the United States have been brought forward several hours to avoid the advancing cyclone.

In February 2016, 44 people were killed when Cyclone Winston destroyed tens of thousands of homes and caused an estimated US$1 billion (S$1.35 billion) in damage when it hit Fiji.