Suva: Fiji declared a state of emergency on Tuesday and ordered troops to launch relief operations in northern regions battered by a powerful cyclone.

Cyclone Tomas' onslaught began to weaken on Tuesday, but the scope of destruction was not clear because communications were cut to the outer islands and to northern areas of Vanua Levu, official said.

One death has been reported, and a nationwide curfew was still in effect.

Fiji's National Disaster Council declared a 30-day state of emergency for the country's northern and eastern divisions on Tuesday.

It also ordered troops to be deployed as soon as possible to provide relief, including food, water and basic supplies.

Cyclone Tomas continued to blast through the northern Lau and Lomaiviti island groups and the northern coast of Vanua Levu on Tuesday, the nation's weather office said.

Matt Boterhoven, Fiji's Tropical Cyclone Center's senior forecaster, said Tomas was still a Category 4 storm, but was expected to weaken to Category 3 by late Tuesday.

National Disaster Management Office spokesman Anthony Blake said power, water, sewage and other services were disrupted in many northern areas.

Airstrips and airports closed and storm surges smashing into coastal villages and schools. More than 17,000 people were in 240 government shelters, he said.

Initial damage assessments will likely be made Wednesday, when airplanes are expected to survey the northern islands and Vanua Levu, Blake said.

The country's military leader, Commodore Frank Bainimarara, has appealed for international assistance, New Zealand Foreign Minister Murray McCully said.