A TROPICAL cyclone heading for Fiji may be the worst cyclone to ever strike the South Pacific nation.

Fiji Meteorological Service senior forecaster, Matt Boterhoven, said Cyclone Tomas had intensified overnight and was now a category four storm.

Mr Boterhoven said the northern island of Vanua Levu was most at risk, with winds likely to peak at over 200km/h in the next 24 hours.

"There's going to be a whole lot of flooding," he said late this morning.

"(It's a) very destructive hurricane force area so they'll be getting quiet a battering over the next 12 hours."

According to local media reports, Cyclone Tomas claimed its first victim yesterday, when 31-year-old Fijian woman was killed trying to save her family from being washed away in huge waves that crashed into the coast of Vanua Levu.

A spokeswoman for Fiji Police, Ema Mua, said the nation was undertaking last minute preparations for a "disastrous" thrashing.

"We were looking at the difference between the forces of all the cyclones that have happened in Fiji," said Mua, as her colleagues hammered boards to windows.

"It's moving very, very slowly but at the same time it's picking up a lot, a lot, of force.

"That is why the categories have been proceeding.

"If it doesn't lessen down then it could be the worst to ever hit the country."

Australian tourist, Clare Melvin, said she was evacuated from her accommodation at Plantation Island yesterday afternoon.

"They basically said to us, 'If you've got kids, you should go'," Ms Melvin said.

She had been holidaying in Fiji with her husband and two small children for a week.

"Everybody just jumped on this big boat and came back (to the mainland) and they just threw our luggage on the ground and we just all had to scramble for it," she said.

"It was ridiculous."

She said women were crying in the hotel lobby and everyone was "pretty scared".

"All the Fijians are kind of freaking out themselves, you can tell, cause there's no animals around," the Sydneysider said.

"It's unusually still. It's really weird.

"It's just overcast and kind of dark, but yesterday afternoon the sky was a really strange colour, it was like dark orange and black."

Tourism Fiji said Air New Zealand and V-Australia had cancelled all Fiji services until further notice and Air Pacific said it would postpone flights to Fiji ex-Auckland, Brisbane and Sydney until tomorrow.

Originally published as Fiji bunkers down for 'worst cyclone ever'