Hundreds of tourists have been stranded in Fiji after flooding closed the main road to the island's international airport.

Fiji's leaders have already officially declared a state of natural disaster in the flood-ravaged country, with more heavy rain forecast to be on the way.

Close to 7,000 people have been forced to seek shelter in evacuation centres as heavy rain sweeps across the island of Viti Levu.

National carrier Air Pacific has cancelled all flights into Fiji because passengers have no way of reaching their hotels, while the interim government has temporarily halted passenger flights into the country.

Virgin Airlines has also cancelled four flights which were due to leave today.

DFAT says officials are in regular contact with Fiji's disaster management office and will continue to confirm the whereabouts and safety of Australians in the affected areas.

Two people have been confirmed dead, with one man killed when he was trapped in his car by floods and another swept away in a creek.

Meteorologist Neville Koop says the damage bill is likely to be in the millions.

"We've seen very significant infrastructure damage," he said.

"Unlike the floods in January, where we did have some notice of them coming and people in and around Nadi especially had the chance to move goods and property beforehand.

"In this case it's just caught everybody by surprise and so the level of damage is just going to be tremendous."